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PubMed2006

Association of daytime napping and Parkinsonian signs in Alzheimer's disease.

BACKGROUND AND PURPOSE: Excessive daytime sleepiness (EDS) is reported in Alzheimer's disease (AD), with unstable sleep-wake rhythms that worsen with advancing disease stage. EDS is also very common in Parkinson's disease (PD), regardless of disease severity. The purpose of this study was to determine whether more Parkinsonian motor signs exist in AD patients with more reported daytime napping compared to AD patients without daytime napping. PATIENTS AND METHODS: AD patients ((National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association) NINCDS/ADRDA criteria) were prospectively evaluated in a dementia clinic. Parkinsonian motor signs were assessed using a modified motor Unified Parkinson's Disease Rating Scale (mmUPDRS). AD patients were grouped according to daytime napping frequency: (1) minimal napping (AD-Naps), or (2) napping at least once a day (AD+Naps). Wilcoxon rank-sum tests and chi2-tests computed differences between groups for mmUPDRS, nighttime sleep disturbances, and the Mini Mental State Examination (MMSE). Statistical significance was set at P<0.05. RESULTS: AD patients were classified as AD-Naps (n=155) or AD+Naps (n=180). Compared with AD-Naps patients, AD+Naps patients had higher total mmUPDRS scores (P<0.001), higher rigidity scores (P<0.005), and more gait impairment (P<0.001). CONCLUSION: AD patients with more reported daytime napping had more Parkinsonian motor signs, suggesting that this subgroup may have an increased propensity for sleepiness resembling PD. Longitudinal studies with objective measures are needed to determine whether causal relationships exist between sleepiness and Parkinsonism in AD.

Adult↗

PubMed2003

Using electrostatic potentials to predict DNA-binding sites on DNA-binding proteins.

A method to detect DNA-binding sites on the surface of a protein structure is important for functional annotation. This work describes the analysis of residue patches on the surface of DNA-binding proteins and the development of a method of predicting DNA-binding sites using a single feature of these surface patches. Surface patches and the DNA-binding sites were initially analysed for accessibility, electrostatic potential, residue propensity, hydrophobicity and residue conservation. From this, it was observed that the DNA-binding sites were, in general, amongst the top 10% of patches with the largest positive electrostatic scores. This knowledge led to the development of a prediction method in which patches of surface residues were selected such that they excluded residues with negative electrostatic scores. This method was used to make predictions for a data set of 56 non-homologous DNA-binding proteins. Correct predictions made for 68% of the data set.

Binding Sites↗

PubMed1999

The requirement for pertussis to induce EAU is strain-dependent: B10.RIII, but not B10.A mice, develop EAU and Th1 responses to IRBP without pertussis treatment.

PURPOSE: Experimental autoimmune uveoretinitis (EAU) in mice is an important model for elucidating basic mechanisms in autoimmune eye disease. The need for pertussis toxin (PTX) as an additional adjuvant to elicit EAU has limited the usefulness of this model in some types of studies by introducing a pleiotropic factor with confounding effects on the immune response. METHODS: In the present study the authors examined the ability of B10.RIII mice, the most susceptible strain known so far, to develop EAU in response to the retinal antigen, interphotoreceptor retinoid-binding protein (IRBP), and to a major uveitogenic epitope of IRBP, peptide (p)161-180, in the absence of PTX treatment. RESULTS: The data indicate that high disease scores in response to IRBP and p161-180 were found in B10.RIII mice, without the need for PTX as part of the immunization protocol. Unlike the B10.A strain in which appreciable disease did not develop without PTX, B10.RIII mice mounted a high IFN-gamma response to IRBP in the absence of PTX treatment. Interestingly, and unlike the effect with IRBP, in vitro recall response to p161-180 was low in IFN-gamma, despite good EAU scores. CONCLUSIONS: The data indicate that an important mechanism through which PTX facilitates induction of cell-mediated autoimmunity is by promoting a Th1 polarization of the immune response. The propensity of B10.RIII mice to mount a more polarized Th1 response to IRBP than other strains may contribute to their ability to develop EAU without pertussis adjuvant. Nevertheless, the induction of EAU by p161-180 in the context of a relatively limited IFN-gamma production indicates that non-Th1- and Th-related mechanisms are likely to act in concert to determine the outcome of disease.

Adjuvants, Immunologic↗

PubMed1991

Folding and function of the myelin proteins from primary sequence data.

To explain how the myelin proteins are involved in the organization and function of the myelin sheath requires knowing their molecular structures. Except for P2 basic protein of PNS myelin, however, their structures are not yet known. As an aid to predicting their molecular folding and possible functions, we have developed a FORTRAN program to analyze the primary sequence data for proteins, and have applied this to the myelin proteins in particular. In this program, propensities for the secondary structure conformations as well as physical-chemical parameters are assigned to the amino acids and the pattern of these parameters is examined by calculating their average values, autocorrelation functions and Fourier transforms. To compare two proteins, their sequences are aligned using a unitary scoring matrix, and homologies are searched by plotting a two-dimensional map of the correlation coefficients. Comparison of the corresponding myelin basic proteins (MBP) and P0 glycoproteins (P0) for rodent and shark showed that the conserved residues included most of the amino acids which were predicted to form the alpha or beta conformations, while the altered residues were mainly in the hydrophilic and turn or coil regions. In both rodent and shark the putative extracellular domain of P0 glycoprotein displayed consecutive peaks of beta propensity similar to that for the immunoglobulins, while the cytoplasmic domain showed alpha-beta-alpha folding. To trace the immunoglobulin fold along the P0 sequence, we compared the beta propensity curve of P0 with that of the immunoglobulin M603, whose three-dimensional structure has been determined. We propose that the flat beta-sheets of P0 are orientated parallel to the membrane surface to facilitate their homotypic interaction in the extracellular space. An extra beta-fold in the extracellular domain of shark P0 compared with rodent P0 was found, and this may result in a greater attraction between the apposed extracellular surfaces and may account for a smaller extracellular space as measured by x-ray diffraction. A computer search of the myelin protein sequences for functional motifs revealed sites for N-glycosylation, phosphorylation, nucleotide binding, and certain enzyme activities. We note especially that there are potential nucleotide binding sites in proteolipid protein (PLP), MBP and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP). This is consistent with the experimental observations that PLP acts like an ionophore or proton channel when reconstituted into planar lipid bilayers, MBP binds GTP, and CNP catalyzes in vitro the hydrolysis of 2',3'-nucleotides into corresponding 2'-nucleotides.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗

PubMed2005

Daytime sleepiness in mild and moderate Alzheimer's disease and its relationship with cognitive impairment.

The increased tendency to fall asleep during the daytime together with increased wakefulness during the night has been demonstrated in patients with advanced Alzheimer's disease (AD). The aim of this study was to assess daytime sleep propensity in a cohort of patients with mild/moderate AD and to correlate it with cognitive impairment. Twenty drug-free AD patients meeting the NINCDS-ADRDA criteria for probable AD were evaluated. According to their Clinical Dementia Rating scores, subjects were classified into mild (CDR1; n=11) and moderate (CDR2; n=9) dementia patients. A group of 12 healthy subjects was taken as controls. The subjects were evaluated by the multiple sleep latency test (MSLT) after their nocturnal sleep pattern had been assessed by a polysomnographic recording throughout the night before. Both groups of AD patients showed a higher level of daytime sleepiness, which was statistically significant for mean daytime sleep latency (MDSL) (controls versus CDR1 and versus CDR2, CDR1 versus CDR2) and for 10:00 and 12:00 hour naps (controls versus CDR1, controls versus CDR2). In the entire group of AD patients, MDSL was significantly related with MMSE, De Renzi's Token test, verbal fluency, verbal digit span, story recall, Raven's Progressive Matrices, Weigl test and Benton's three-dimensional test. These data indicate that an increased sleep propensity during daytime occurs also in patients with mild/moderate AD detected by objective neurophysiological techniques.

Aged↗

PubMed2005

Interleukin-8 in whole blood and clinical status in cystic fibrosis.

Cytokines and polymorphonuclear leukocytes play a key role in immune mediated inflammation in progressive pulmonary damage due to cystic fibrosis. The aim of this study is to establish a simple measure of the host's propensity to secrete inflammatory cytokines and to correlate this with clinical status. Patients (n=44, median age 16 years) with the DeltaF 508 mutation (homozygous) were grouped according to their Shwachman score: Patients with mild disease (Shwachman score 71-100 points, group A, n=22, median FEV(1) 79%) were compared with those with more severe disease (Shwachman score 41-55 points, group B, n=22, median FEV(1) 55%) and age-matched controls (group C, n=22, median FEV(1) 102%). Whole blood was stimulated with 5 ng of lipopolysaccharide (LPS). Interleukin-8 (IL-8) was measured by chemiluminescent immunometric assay (DPC, Bad Nauheim, Germany). Though there was a significant difference at baseline for IL-8 (median group A/B/C 6.1/30.5/5.8 pg/ml; p<0.001), there was no significant difference after stimulation. Moreover, in Pseudomonas aeruginosa positive (Psa+) patients (n=26) there was a significant negative correlation (r=-0.539; p<0.004) between baseline IL-8 and FEV(1) (%). Clinical course and lung function (in Psa+) correlate with IL-8 levels.

Adolescent↗

PubMed2006

Additive effects of combined blockade of AT1 receptor and HMG-CoA reductase on left ventricular remodeling in infarcted rats.

Both angiotensin receptor antagonists and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been shown to attenuate cardiomyocyte hypertrophy after myocardial infarction. Whether combination treatment may be superior to either drug alone on cardiomyocyte hypertrophy remains unclear. After ligation of the left anterior descending artery, rats were randomized to both, one, or neither of the angiotensin receptor antagonists olmesartan (0.01, 0.1, 1, and 2 mg.kg-1.day-1) and HMG-CoA reductase inhibitor pravastatin (5 mg.kg-1.day-1) for 4 wk. Each drug, when given alone, decreased cardiomyocyte sizes isolated by enzymatic dissociation at the border zone when compared with vehicles. However, compared with either drug alone, combined olmesartan and pravastatin prevent cardiomyocyte hypertrophy to a larger extent, which was further confirmed by downregulation of the left ventricular atrial natriuretic peptide mRNA. The myocardial endothelin-1 levels at the border zone were 6.5-fold higher (P<0.0001) in the vehicle group compared with the sham group, which can be inhibited after pravastatin administration. Combination treatment significantly attenuated cardiomyocyte hypertrophy in a dose-dependent manner, although tissue endothelin-1 levels remained stable in combination groups of different olmesartan doses. Measurements of the arrhythmic score mirrored those of cardiomyocyte hypertrophy. Dual therapy with pravastatin and olmesartan, which produced an additive reduction in cardiomyocyte hypertrophy and cardiac fibrosis after myocardial infarction through different mechanisms, decreases the propensity of the heart to arrhythmogenesis. Pravastatin administration provided favorable ventricular remodeling, probably through decreased tissue endothelin-1 level. In contrast, olmesartan-related attenuated cardiomyocyte hypertrophy is independent of endothelin-1 pathway.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2006

Schizotypy and creativity in visual artists.

'Every work of art is an uncommitted crime' Adorno (1951). Cited in Julius (2002). Given the putative relationship between creativity and schizotypy/psychoticism, the current study set out to investigate differences in scores on a range of personality and creativity measures between visual artists and non-artists. Results found that the visual artists group scored higher on measures of positive-schizotypy, disorganized-schizotypy, asocial-schizotypy, neuroticism, openness and divergent thinking (uniqueness) than did the non-artist group and lower on agreeableness. These findings lend support to other studies reporting higher schizotypy scores in artistic and creative cohorts, although provide some of the first evidence of higher unusual experiences and impulsive nonconformity scores on the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE) in visual artists. The relationship between creativity and schizotypy is discussed in terms of unusual ideas and a propensity to endorse socially undesirable responses.

Adult↗

PubMed2006

Selected organizational outcome correlates of spirituality in the workplace.

This study addressed the feasibility, practicality, and effects of a management style defined as "Management-by-Virtues," a management philosophy and practice based on virtues derived from religious beliefs. The study focused on Management-by-Virtues as practiced in Christian firms and assessed the effect that Management-by-Virtues could have on such organizational outcomes as employees' Organizational Commitment, Job Satisfaction, and propensity to go beyond the call of duty in carrying out organizational tasks, i.e., Organizational Citizenship Behavior. The study, based on survey responses from 328 employees of 26 business firms, compared overall scores on Organizational Commitment, Job Satisfaction, and Organizational Citizenship Behavior in 10 businesses, described by owner/managers as being managed according to Christian beliefs and practices, with the same outcomes in 16 "control" firms that did not explicitly espouse such an orientation. The Management-by-Virtues firms were characterized by more committed, more satisfied employees, and employees' reports of higher incidence of Organizational Citizenship Behavior than the comparison firms. However, a measure of this construct based on employees' perceptions did not sharply differentiate the two groups of firms.

Humans↗

PubMed1995

Risk factors towards self-destructive behaviour among fresh students at Makerere University.

It has been suggested that some individuals are suicide prone, and that such individuals can be detected long before they commit suicide. This paper reports the risk factors associated with potential self-destructive behaviour among a group of freshmen and freshwomen at Makerere University. A suicide proneness questionnaire, the Umzimkulu Suicide Proneness Inventory (USPI), was completed by 619 students admitted to the university in the academic year 1992/93. The results indicate that students' propensity to self-destructive behaviour was significantly related to the history of suicide behaviour among the students, or their relatives, and the presence of a probable depressive disorder as indicated by scores above at least 60 on each of SR, AL, AS, and PDW, scales on the questionnaire. The paper describes in detail the development of the USPI, and the theory underlying the study. Implications for improving counselling services for students at Makerere University are highlighted.

Adolescent↗

PubMed1998

Tissue markers as predictors of postoperative adhesions.

BACKGROUND: Postoperative adhesion formation has been associated with a decreased capacity to degrade intra-abdominally deposited fibrin. Adhesions, once lysed, have a high propensity for reformation. This study tested the hypothesis that patients with a high propensity for adhesion formation as well as adhesion tissue had a reduced fibrinolytic capacity. METHODS: Peritoneal biopsies were taken during abdominal surgery from 21 patients who had previously undergone operation; previously formed adhesion tissue was sampled from ten of these patients. Adhesion formation was scored. The fibrinolytic capacity of peritoneum was determined in tissue extracts. RESULTS: At the time of opening of the abdominal cavity, levels of plasminogen activator inhibitor (PAI) type 1 (P = 0.009) and tissue-type plasminogen activator (tPA)/PAI complex (P = 0.008) were increased in peritoneal samples from patients with severe adhesions compared with those in samples from patients with less severe adhesions. Adhesion tissue similarly had reduced fibrinolytic capacity as judged by a decrease in tPA activity (P = 0.005) and an increase in PAI-1 level (P = 0.01), reflected in an increased level of tPA/PAI complex (P = 0.008) compared with unaffected peritoneum. CONCLUSION: These observations demonstrate reduced fibrinolytic capacity in peritoneal tissue in patients with a greater propensity for development of adhesions and likewise in adhesion tissue. This suggests that components of the fibrinolytic system may be used as markers of an increased risk of adhesion development.

Biomarkers↗

PubMed2002

Ziprasidone: a review of its use in schizophrenia and schizoaffective disorder.

UNLABELLED: Ziprasidone is a novel antipsychotic agent with a pharmacological profile distinct from that of other currently available novel or classical antipsychotics. In preclinical studies, ziprasidone was predicted to have efficacy against positive, negative and affective symptoms of schizophrenia with a favourable tolerability profile, including a low propensity to induce extrapyramidal adverse effects. The drug has been administered orally to >300 patients with an acute exacerbation of schizophrenia or schizoaffective disorder in published 4- to 6-week randomised, double-blind trials. When given twice daily, at dosages of between 80 and 160 mg/day, ziprasidone produced significantly greater improvements in overall symptomatology than placebo. In the largest study, ziprasidone 80 or 160 mg/day was also significantly more effective than placebo in reducing negative symptoms and, at 160 mg/day, was significantly more effective than placebo in improving depressive symptoms in patients with associated clinically significant depression. Data from a 4-week trial indicate that ziprasidone 160 mg/day has similar efficacy to haloperidol 15 mg/day. Ziprasidone 40 to 160 mg/day was more effective than placebo with respect to prevention of impending relapse and improvement of negative symptoms in 294 stable patients with chronic schizophrenia who were treated for up to 1 year. In addition, significantly more ziprasidone than haloperidol recipients achieved a negative symptom response in a 28-week study involving 301 stable patients with chronic or subchronic schizophrenia. In general, oral ziprasidone is well tolerated with an overall incidence of adverse events similar to placebo. Importantly, the drug has a low propensity to induce extrapyramidal effects and a negligible effect on bodyweight. Ziprasidone is associated with slight prolongation of the QTc interval; the clinical significance of this is not yet clear. The drug does not appear to be associated with sustained elevation of plasma prolactin concentrations. Preliminary data indicate that long-term oral ziprasidone treatment is well tolerated. Ziprasidone is the only novel antipsychotic currently available in a rapid-acting intramuscular formulation. Short-term treatment with intramuscular ziprasidone was effective and well tolerated in patients with acute agitation associated with psychosis. In addition, intramuscular ziprasidone reduced agitation scores by a significantly greater extent than haloperidol in a study involving patients with acute agitation associated with psychosis. CONCLUSIONS: Ziprasidone is a promising new antipsychotic that has shown significant efficacy in the oral treatment of patients with schizophrenia or schizoaffective disorder. The drug is well tolerated with a low propensity to induce extrapyramidal effects and a negligible effect on bodyweight. In addition, intramuscular ziprasidone shows efficacy and good tolerability in the treatment of acute agitation associated with psychotic disorders.

Administration, Oral↗

PubMed2002

Spotlight on ziprasidone in schizophrenia and schizoaffective disorder.

UNLABELLED: Ziprasidone is a novel antipsychotic agent with a pharmacological profile distinct from that of other currently available novel or classical antipsychotics. In preclinical studies, ziprasidone was predicted to have efficacy against positive, negative and affective symptoms of schizophrenia with a favourable tolerability profile, including a low propensity to induce extrapyramidal adverse effects. The drug has been administered orally to >300 patients with an acute exacerbation of schizophrenia or schizoaffective disorder in published 4- to 6-week randomised, double-blind trials. When given twice daily at dosages of between 80 and 160 mg/day, ziprasidone produced significantly greater improvements in overall symptomatology than placebo. In the largest study, ziprasidone 80 or 160 mg/day was also significantly more effective than placebo in reducing negative symptoms and, at 160 mg/day, was significantly more effective than placebo in improving depressive symptoms in patients with associated clinically significant depression. Data from a 4-week trial indicate that ziprasidone 160 mg/day has similar efficacy to haloperidol 15 mg/day. Ziprasidone 40 to 160 mg/day was more effective than placebo with respect to prevention of impending relapse and improvement of negative symptoms in 294 stable patients with chronic schizophrenia who were treated for up to 1 year. In addition, significantly more ziprasidone than haloperidol recipients achieved a negative symptom response in a 28-week study involving 301 stable patients with chronic or subchronic schizophrenia. In general, oral ziprasidone is well tolerated with an overall incidence of adverse events similar to placebo. Importantly, the drug has a low propensity to induce extrapyramidal effects and a negligible effect on bodyweight. Ziprasidone is associated with slight prolongation of the QTc interval; the clinical significance of this is not yet clear. The drug does not appear to be associated with sustained elevation of plasma prolactin levels. Preliminary data indicate that long-term oral ziprasidone treatment is well tolerated. Ziprasidone is the only novel antipsychotic currently available in a rapid-acting intramuscular formulation. Short-term treatment with intramuscular ziprasidone was effective and well tolerated in patients with acute agitation associated with psychosis. In addition, intramuscular ziprasidone reduced agitation scores by a significantly greater extent than haloperidol in a study involving patients with acute agitation associated with psychosis. CONCLUSIONS: Ziprasidone is a promising new antipsychotic that has shown significant efficacy in the oral treatment of patients with schizophrenia or schizoaffective disorder. The drug is well tolerated with a low propensity to induce extrapyramidal effects and a negligible effect on bodyweight. In addition, intramuscular ziprasidone shows efficacy and good tolerability in the treatment of acute agitation associated with psychotic disorders.

Antipsychotic Agents↗

PubMed2001

The beta-beta-alpha fold: explorations in sequence space.

The computational redesign of the second zinc finger of Zif268 to produce a 28 residue peptide (FSD-1) that assumes a betabetaalpha fold without metal binding was recently reported. In order to explore the tolerance of this metal-free fold towards sequence variability, six additional peptides resulting from the ORBIT computational protein design process were synthesized and characterized. The experimental stabilities of five of these peptides are strongly correlated with the energies calculated by ORBIT. However, when a peptide with a mutation in the beta-turn is examined, the calculated stability does not accurately predict the experimentally determined stability. The NMR solution structure of a peptide incorporating this mutation (FSD-EY) reveals that the register between the beta-strands is different from the model structure used to select and score the sequences. FSD-EY has a type I' turn instead of the target EbaaagbE turn (rubredoxin knuckle). Two additional peptides that have improved side-chain to backbone hydrogen bonding and turn propensity for the target turn were characterized. Both are of stability comparable to that of FSD-1. These results demonstrate the robustness of the ORBIT protein design methods and underscore the need for continued improvements in negative design.

Algorithms↗

PubMed1995

Persistent catalepsy associated with severe dyskinesias in rats treated with chronic injections of haloperidol decanoate.

Patients who develop persistent parkinsonism while on chronic neuroleptic therapy may be predisposed towards the development of tardive dyskinesia (TD). We investigated this issue in an animal model of TD by examining the association between catalepsy and the syndrome of neuroleptic-induced vacuous chewing movements (VCMs). VCMs were measured every 3 weeks for 33 weeks while rats received injections of haloperidol decanoate. Catalepsy was measured after the second through the seventh injections of the depot neuroleptic. There were no correlations between the severity of catalepsy scores after the second or third injections of haloperidol and the severity of the overall VCM syndrome. However, the severity of the catalepsy score following the third through seventh injections of haloperidol strongly correlated with the concurrent number of VCMs. Persistent high catalepsy scores across the six catalepsy rating sessions were strongly associated with the development of persistent severe VCMs. These findings suggest that, to the extent that persistent parkinsonian signs in humans are associated with a propensity towards the development of TD, the VCM syndrome in rats is at least a partially faithful animal model of this relationship.

Animals↗

PubMed1997

Evidence that adult life risk factors influence the expression of familial propensity to breast cancer.

In the context of a study in Athens comprising 692 cases and 1,261 controls, we have evaluated the effect on breast cancer risk of the joint action of first-degree relative family history and established adult life risk factors. We created a risk score by assigning the value of 1 to women at high risk with respect to any of these risk factors and 0 otherwise, and summing these values, using weights equal to the excess odds ratio. The odds ratio for a tertile increment in the risk score was 1.5 [95% confidence interval (CI) = 1.3-1.8] among women without family history, and 2.3 (95% CI = 1.1-5.1) for women with family history. Our findings imply that women with a family history of breast cancer may benefit disproportionately by reduced exposure to adult life risk factors.

Adult↗

PubMed1983

Functional implications of skeletal diversity in two South American tamarins.

This study examines the relationship between positional behavior and morphology for two closely related South American tamarin species, Saguinus fuscicollis illigeri and Saguinus oedipus oedipus. Although never systematically documented, the two species are suspected of exhibiting highly similar yet subtly different locomotor behaviors with a greater propensity for climbing, springing, and more powerful leaping in S. oedipus. Fourteen measurements reflecting biomechanical structuring were taken from the postcranial skeleton of 28 individuals of each species. The data were reduced to principal component scores and subjected to a multiple analysis of variance to determine the extent of intergroup skeletal variation. Areas of significant skeletal diversity were interpreted functionally. The results suggest that the differences in functional patterning among the two species is consistent with the behavioral hypothesis. It is concluded that subtle changes in positional behavior may be capable of altering skeletal morphology.

Analysis of Variance↗

PubMed2006

An algorithm for predicting protein-protein interaction sites: Abnormally exposed amino acid residues and secondary structure elements.

Multiprotein systems mediate most regulatory processes in living organisms. Although the structures of the individual proteins are often defined, less is known of the structures of multiprotein systems. Computational methods for predicting interfaces, using evolutionary conservation and/or physicochemical data, have been developed. Here we consider the use of solvent accessibility, residue propensity, and hydrophobicity, in conjunction with secondary structure data, as prediction parameters. We analyze the influence of residue type and secondary structure on solvent accessibility and define a measure of "relative exposedness." Clustering abnormally high scoring residues provides a basis for predicting interaction sites. The analysis is extended to investigate abnormally exposed secondary structure elements, particularly beta-sheet strands. We show that surface-exposed beta-strands lacking protective features are more likely to be found at protein-protein interfaces, allowing us to create an algorithm with approximately 68% and approximately 75% accuracy in differentiating between interacting and edge strands in isolated beta-strands and beta-sheet strands, respectively. These methods of identifying abnormally exposed surface regions are combined in an algorithm, which, on a data set of 77 unbound and disjoint (single chain extracted from complex) structures, predicts 79% of the protein-protein interfaces correctly. If enzyme-inhibitor complexes, where the inhibitor mimics a nonprotein substrate, are excluded, the accuracy increases to 85%.

Algorithms↗