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Biomedical subjects

J M Moreno

Publications and source records attributed to J M Moreno.

At least 37 records · Page 2Linked to original sources
PubMed2003

De novo malignancies and liver transplantation.

INTRODUCTION: De novo tumors (DNTs) are the leading cause of late death among liver transplant recipients with an incidence of 5% to 15%, which is significantly greater than the general population. In this retrospective study, we compared this complication in liver transplant recipients to sex- and age-matched controls. PATIENTS: Among 410 patients who received liver allografts between March 1986 and December 2000, 32 (7.8%) developed a DNT. Epidermoid tumors were the most frequent histologic lineage. A complete response was observed in 19 patients (59.4%), a partial response in eight (25%), and no response in five (15%). Survival was lower among liver transplant recipients than controls, a difference that was statistically significant. Treatment consisted of surgery in 76.7%, radiotherapy in 16.7%, chemotherapy in 13.3%, and reduction of immunosuppression in 10%. RESULTS: The mean survival time in transplant patients of 122.97 months (95% CI; range 98-147 months) was significantly shorter than controls, 156.5 months (95% CI; range 141-171 months). About 50% of patients were smokers (active or ex-smokers), compared to 20.7% of controls (P=.049). Significant differences were also found when the three subgroups (smokers, previous smokers, and nonsmokers) were analyzed separately (P=.013). Patients were smokers (active or nonactive) among 45% of cases of skin tumors; 60% of hematological tumors; 71.4% of epidermoids; and 33% of sarcomas. CONCLUSIONS: DNTs, a complication of long-term immunosuppression in patients after liver transplantation, most frequently presented as skin tumors and PTLD. Occurrence of a DNT was an adverse prognostic factor for survival. Smoking represents an independent risk factor for these tumors.

Adult↗
PubMed2002

[Neurohagiography. Lamberto Caesaraugustanus, the cephalophoric: holy patron of Spanish neurology?].

Until now Neurology has lacked a patron saint who, taking the most advantage of the rich cultural tradition inherited from our past and independently of the religious ideology of each one, can be helpful approach in the neurologist figure to different people. An Ad Hoc Committee from the Neurology History Study Group of the SEN has researched the medical hagiography with any kind of neurological relationship (neurohagiography), in order to make a hagiography study of every saint related to our speciality, with the added luck of proposing a patron for Neurology with hispanic origin. In this pioneer study of historiographic research different documents related with the medical hagiography have been studied, especially the Index ac Status Causarum, and information coming from different national ecclesiastic archives. A total of 342 saints share the patronage of 137 diseases, of which a 27,7% are related in some way to Neurology. Headache constitutes the prime cause of the invocations, with 20 saints. Another 11 saints plead for epilepsy; to these we also must add another six for so called possessed patients. Therefore, two of the three main causes of invocation (headache, fever and epilepsy) come up to chronic processes. Of all the saints with a hispanic origin candidates to the patronage of the neurologists San Lamberto Caesaraugustanus stands out, who died in the year 303 during Diocletian persecution. Belonging to the selected standing of "cephalophoric martyrs" (those beheahed who carry their own head in their hands), he was able to walk an important distance (about six kilometres) with his head split from the body, a fact only understood as a suprahuman phenomenon thanks to which he has becomes the brain transplant pioneer.

History, 16th Century↗
PubMed2001

Cyano-bridged bimetallic assemblies from hexacyanometalate, [M(CN)6](3-) (M = Mn(III) and Fe(III)), and [M(N4-macrocycle)]2+ (M=Fe(III), Ni(II) and Zn(II)) building blocks. Syntheses, multidimensional structures, and magnetic properties.

Reactions between [M(N(4)-macrocycle)](2+) (M = Zn(II) and Ni(II); macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)(6)](3-) (M = Fe(III) and Mn(III)) give rise to cyano-bridged assemblies with 1D linear chain and 2D honeycomblike structures. The magnetic measurements on the 1D linear chain complex [Fe(cyclam)][Fe(CN)(6)].6H(2)O 1 points out its metamagnetic behavior, where the ferromagnetic interaction operates within the chain and the antiferromagnetic one between chains. The Neel temperature, T(N), is 5.5 K and the critical field at 2 K is 1 T. The unexpected ferromagnetic intrachain interaction can be rationalized on the basis of the axially elongated octahedral geometry of the low spin Fe(III) ion of the [Fe(cyclam)](3+) unit. The isostructural substitution of [Fe(CN)(6)](3-) by [Mn(CN)(6)](3-) in the previously reported complex [Ni(cyclam)](3)[Fe(CN)(6)](2).12H(2)O 2 leads to [Ni(cyclam)](3)[Mn(CN)(6)](2).16 H(2)O 3, which exhibits a corrugated 2D honeycomblike structure and a metamagnetic behavior with T(N) = 16 K and a critical field of 1 T. In the ferromagnetic phase (H > 1 T) this compound shows a very important coercitive field of 2900 G at 2 K. Compound [Ni(CTH)](3)[Fe(CN)(6)](2).13H(2)O 4, C(60)H(116)Fe(2)N(24)Ni(3)O(13), monoclinic, A 2/n, a = 20.462(7), b = 16.292(4), c = 27.262(7) A, beta = 101.29(4) degrees, Z = 4, also has a corrugated 2D honeycomblike structure and a ferromagnetic intralayer interaction, but, in contrast to 2 and 3, does not exhibit any magnetic ordering. This fact is likely due to the increase of the interlayer separation in this compound. ([Zn(cyclam)Fe(CN)(6)Zn(cyclam)] [Zn(cyclam)Fe(CN)(6)].22H(2)O.EtOH) 5, C(44)H(122)Fe(2)N(24)O(23)Zn(3), monoclinic, A 2/n, a = 14.5474(11), b = 37.056(2), c = 14.7173(13) A, beta = 93.94(1) degrees, Z = 4, presents an unique structure made of anionic linear chains containing alternating [Zn(cyclam)](2+) and [Fe(CN)(6)](3)(-) units and cationic trinuclear units [Zn(cyclam)Fe(CN)(6)Zn(cyclam)](+). Their magnetic properties agree well with those expected for two [Fe(CN)(6)](3-) units with spin-orbit coupling effect of the low spin iron(III) ions.

Journal Article↗
PubMed2001

Changes in the rate of tubal ligation done after cesarean section.

OBJECTIVE: We studied tubal ligations done after cesarean section in a Spanish hospital during a 20-year period, in order to analyze changes in patient characteristics and indications for cesarean delivery. STUDY DESIGN: We reviewed the clinical records, for the period from 1978 to 1997, of 1996 cases of cesarean section followed by tubal ligation in 108776 births in which the fetus weighed 1000 g or more. RESULTS: During the 20-year period of study, the proportion of cesarean sections relative to vaginal deliveries increased, as did the frequency of cesarean section followed by tubal ligation relative to cesarean and vaginal deliveries. The proportion of women who underwent tubal ligation after a second cesarean section decreased from 60% during 1978-1982 to 5.6% during 1993-1997. The most frequent maternal pathology associated with gestation was previous cesarean section (60.5%), although 50% of the women had no underlying pathology. CONCLUSIONS: In our setting, the rate of cesarean section followed by tubal ligation has been increasing steadily since the early 1980s. The proportion of women who requested tubal sterilization and who had only one living child, or who had had a previous cesarean birth, also increased.

Adolescent↗
PubMed2001

Evaluation of nonglucose carbohydrates in parenteral nutrition for diabetic patients.

OBJECTIVE: There is little information on the advantages of nonglucose carbohydrates in total parenteral nutrition (TPN) for diabetic patients. The aim of this study is to evaluate glycemic control and insulin requirements in diabetic patients who received TPN with different sources of carbohydrates, and to determine whether insulin requirements are different when septic and non-septic diabetic patients are studied. MATERIALS AND METHODS: One-hundred and thirty-eight patients were randomly divided into two groups receiving either glucose (G), n=71, or glucose-fructose-xylitol 2:1:1 (GFX), n=67. There were no differences between the demographic or anthropometric characteristics of the groups, nor between the patients with diabetes mellitus type 1 and type 2, nor the initial TPN composition. Acceptable glycemic control was considered when glycemia reached <200 mg/dl. RESULTS: Glycemic control was attained in 79.7% of patients (74.6 vs 85.1%), in the same period of treatment. At the end of treatment, insulin requirements were not different (45+/-19 vs 45+/-26 UI/day) in both groups, while similar amounts of carbohydrates (191+/-36 vs 187+/-45 g/day) were infused. The ratio insulin/body weight and insulin/carbohydrates were equal in both groups. In the GFX group nonseptic and septic patients needed less and more insulin, respectively, than their counterparts in the G group. No major adverse events related to carbohydrate infusions were observed. CONCLUSIONS: Either G or GFX could be used in TPN for diabetic patients, providing glycemic control in most cases with similar insulin requirements. GFX mixtures were slightly more beneficial to attain glycemic control in nonseptic patients, but septic diabetic patients had higher insulin needs in this group.

Aged↗
PubMed2001

Survey on legislation and funding of home artificial nutrition in different European countries.

RATIONALE: Home Artificial Nutrition (HAN) has been an expanding area over the last 30 years. HAN programs have been often developed prior to the regulation by the National Health Systems (NHS) leading to different policies within European countries. The aim of this study was to compare legislation regarding HAN in Europe. METHOD: The Group elaborated two structured questionnaires (one for Home Enteral Nutrition--HEN--and one for Home Parenteral Nutrition--HPN) which were presented to all the members of the HAN-Working group and to the 21 ESPEN Council members. RESULTS: Twelve questionnaires were returned, covering for more than 375 million inhabitants. HEN: regulated in seven countries, Italy and France being the first to implement reimbursement policy in 1988. Except in France, Croatia and the Czech Rep almost any physician can prescribe HEN. NHS totally or partially fund HEN, although in Austria and Israel expenses are paid for the patients. Provision of enteral diets and equipment varies widely within countries. As in HPN, most of the countries have written guidelines for health care workers and for patients. HPN: legislated in six countries, Denmark being the first in 1975. HPN programs are restricted to a few hospitals and patients are followed by Nutrition Support Teams (NST). The budget for HPN is 100% supported by NHS. Hospital pharmacy, private pharmacists and Home Care companies are involved in a different degree in providing and distributing solutions and disposables. CONCLUSIONS: HPN regulation preceded HEN regulation by 10-20 years. Due to this longer experience and high level of care, HPN patients are usually followed by NST. Despite different policies, funding is relatively uniform, NHS supporting most of the expenses for HAN. ESPEN could play a key role developing common standards for HAN all over Europe.

Enteral Nutrition↗
PubMed2000

Helical-chain copper(II) complexes and a cyclic tetranuclear copper(II) complex with single syn-anti carboxylate bridges and ferromagnetic exchange interactions.

Tridentate Schiff-base carboxylate-containing ligands, derived from the condensation of 2-imidazolecarboxaldehyde with the amino acids beta-alanine (H2L1) and 2-aminobenzoic acid (H2L5) and the condensation of 2-pyridinecarboxaldehyde with beta-alanine (HL2), D,L-3-aminobutyric acid (HL3), and 4-aminobutyric acid (HL4), react with copper(II) perchlorate to give rise to the helical-chain complexes [[Cu(mu-HL1)(H2O)](ClO4)]n (1), [[Cu(mu-L2)(H2O)](ClO4).2H2O]n (2), and [[Cu(mu-L3)(H2O)](ClO4).2H2O]n (3), the tetranuclear complex [[Cu(mu-L4)(H2O)](ClO4)]4 (4), and the mononuclear complex [Cu(HL5)(H2O)](ClO4).1/2H2O (5). The reaction of copper(II) chloride with H2L1 leads not to a syn-anti carboxylate-bridged compound but to the chloride-bridged dinuclear complex [Cu(HL1)(mu-Cl)]2 (6). The structures of these complexes have been solved by X-ray crystallography. In complexes 1-4, roughly square-pyramidal copper(II) ions are sequentially bridged by syn-anti carboxylate groups. Copper(II) ions exhibit CuN2O3 coordination environments with the three donor atoms of the ligand and one oxygen atom belonging to the carboxylate group of an adjacent molecule occupying the basal positions and an oxygen atom (from a water molecule in the case of compounds 1-3 and from a perchlorate anion in 4) coordinated in the apical position. Therefore, carboxylate groups are mutually cis oriented and each syn-anti carboxylate group bridges two copper(II) ions in basal-basal positions with Cu...Cu distances ranging from 4.541 A for 4 to 5.186 A for 2. In complex 5, the water molecule occupies an equatorial position in the distorted octahedral environment of the copper(II) ion and the Cu-O carboxylate distances in axial positions are very large (>2.78 A). Therefore, this complex can be considered as mononuclear. Complex 6 exhibits a dinuclear parallel planar structure with Ci symmetry. Copper(II) ions display a square-pyramidal coordination geometry (tau = 0.06) for the N2OCl2 donor set, where the basal coordination sites are occupied by one of the bridging chlorine atoms and the three donor atoms of the tridentate ligand and the apical site is occupied by the remaining bridging chlorine atom. Magnetic susceptibility measurements indicate that complexes 1-4 exhibit weak ferromagnetic interactions whereas a weak antiferromagnetic coupling has been established for 6. The magnetic behavior can be satisfactorily explained on the basis of the structural data for these and related complexes.

Journal Article↗
PubMed2000

A rational design for imidazolate-bridged linear trinuclear compounds from mononuclear copper(II) complexes with 2-[((imidazol-2-ylmethylidene)amino)ethyl]pyridine (HL): syntheses, structures, and magnetic properties of [Cu(L)(hfac)M(hfac)2Cu(hfac)(L)] (M = ZnII, CuII, MnII).

Two mononuclear copper(II) complexes with the unsymmetrical tridentate ligand 2-[((imidazol-2-ylmethylidene)amino)ethyl]pyridine (HL), [Cu(HL)(H2O)](ClO4)2.2H2O (1) and [Cu(HL)Cl2] (2), have been prepared and characterized. The X-ray analysis of 2 revealed that the copper(II) ion assumes a pentacoordinated square pyramidal geometry with an N3Cl2 donor set. When 1 and 2 are treated with an equimolecular amount of potassium hydroxide, the deprotonation of the imidazole moiety promotes a self-assembled process, by coordination of the imidazolate nitrogen atom to a Cu(II) center of an adjacent unit, leading to the polynuclear complexes [[Cu(L)(H2O)](ClO4)]n (3) and [[Cu(L)Cl].2H2O]n (4). Variable-temperature magnetic data are well reproduced for one-dimensional infinite regular chain systems with J = -60.3 cm(-1) and g = 2.02 for 3 and J = -69.5 cm(-1) and g = 2.06, for 4. When 1 is used as a "ligand complex" for [M(hfac)2] (M = Cu(II), Ni(II), Mn(II), Zn(II)) in a basic medium, only the imidazolate-bridged trinuclear complexes [Cu(L)(hfac)M(hfac)2Cu(hfac)(L)] (M = Zn(II), Cu(II)) (5, 6) can be isolated. Nevertheless, the analogous complex containing Mn(II) as the central metal (7) can be prepared from the precursor [Cu(HL)Cl2] (2). All the trinuclear complexes are isostructural. The structures of 5 and 6 have been solved by X-ray crystallographic methods and consist of well-isolated molecules with Ci symmetry, the center of symmetry being located at the central metal. Thus, the copper(II) fragments are in trans positions, leading to a linear conformation. The magnetic susceptibility data (2-300 K), which reveal the occurrence of antiferromagnetic interactions between copper(II) ions and the central metal, were quantitatively analyzed for symmetrical three-spin systems to give the coupling parameters JCuCu = -37.2 and JCuMn = -3.7 cm(-1) with D = +/-0.4 cm(-1) for 6 and 7, respectively. These magnetic behaviors are compared with those for analogous systems and discussed on the basis of a localized-orbital model of exchange interactions.

Chemical Phenomena↗
PubMed2000

[Home parenteral nutrition. A six-year combined program (adult and pediatric patients)].

BACKGROUND: To describe the outcomes of an adult-pediatric home parenteral nutrition (HPN) program. PATIENTS AND METHODS: Retrospective protocol between 1993 and 1999. RESULTS: Sixteen adults (average 45.7 years) and eight children (3.1 years) were included in the program. Mean length of parenteral nutrition was 507 (SD: 624) and 155 (SD: 129) days respectively. Total follow-up time was 8,119 days for adults and 1,242 for children. Cancer was the main diagnosis in adults and intractable diarrhea in children. Central venous catheter related infections were the most usual complication (0.63 and 1.2 episodes/patient/year). There were no deceases due to the HPN in the period of study. CONCLUSIONS: HPN is an effective and safe technique, although prevalence and incidence in Spain are low.

Adult↗
PubMed2000

Pregnancy in a patient with chronic intestinal pseudo-obstruction on long-term parenteral nutrition.

Parenteral nutrition support is provided in most instances for short intervals during pregnancy in conditions where oral/enteral intake is severely compromised. Few reports describe the use of parenteral nutrition from conception to delivery. We report the case of a 30-year-old woman suffering from a severe form of chronic intestinal pseudo-obstruction on long-term parenteral nutrition because of malabsorption and malnutrition. Pregnancy and delivery developed uneventfully. The fetus grew normally throughout pregnancy. Our patient needed only slight modifications in her parenteral nutrition regimen during lactation. There were no metabolic complications during pregnancy. We conclude that female patients even with severe forms of gastrointestinal diseases, such as chronic intestinal pseudo-obstruction requiring long-term home parenteral nutrition, can conceive and carry successfully a pregnancy to term.

Adult↗
PubMed2000

Macromolecular mimicry in translation initiation: a model for the initiation factor IF2 on the ribosome.

Protein biosynthesis in bacteria is controlled by a number of translation factors. Recent data based on comparison of sequence and structure data of translation factors have established a novel hypothesis for their interaction with the ribosome: initiation, elongation, and termination factors may use a common or partly overlapping binding site on the ribosome in a process of macromolecular mimicry of an A-site-bound tRNA. This paper reviews structural knowledge and tRNA macromolecular mimicry involvement of translation initiation factor IF2. Furthermore, a model is proposed for the factor and its interaction with the ribosome during the formation of the translation initiation complex.

Eukaryotic Initiation Factor-1↗
PubMed2000

Multicenter retrospective study of response to interferon in chronic hepatitis B.

AIM: The only agent known to have a lasting beneficial effect in chronic hepatitis B is interferon alpha, which achieves long-term remission in 25-40% of the patients. The goals of treatment are to induce clearance of HBV DNA from serum, to return serum aminotransferases to normal, and to improve histological findings in the liver. The most important factors predictive of response to treatment are high serum aminotranferases levels, low serum HBV DNA concentrations, and active histologic changes on liver biopsy. The aim of this study was to assess the response to interferon alpha in patients with chronic hepatitis B and to analyze the factors predictive of response. METHODS: We conducted a multicenter retrospective study to investigate the effect of interferon treatment in 132 patients with chronic hepatitis B in overall terms and based on HBeAg, and factors predictive of response. RESULTS: A overall sustained response was noted in 59 of 132 interferon-treated patients (45%) and 61 patients were nonresponders (46%). 12 patients relapsed (9%). None of the patients had negative HBsAg. No difference was observed in the response rate between the two treatment groups (HBeAg-positive and HBeAg-negative patients). Overall, high initial levels of serum AST and ALT predicted a good response. Age and liver biopsy findings were factors predictive of response in HBeAg-positive and HBeAg-negative patients respectively. Sex, epidemiological factors, treatment and type of virus did not correlate with the response to interferon. CONCLUSIONS: A sustained response to interferon alpha was observed in 45% of the patients with chronic hepatitis B. HBeAg seroconversion was found in up to 50% of HBeAg-positive patients. None of the patients had negative HBsAg. Overall, the response rate was higher in patients with high pretreatment serum aminotransferase levels. Age was the predictive factor in HBeAg-positive patients, and histological features were predictive in the HBeAg-negative group. However, further studies in a larger patient population are necessary to obtain well-substantiated conclusions.

Adolescent↗
PubMed1999

Synthesis and characterization of novel palladium(II) complexes of bis(thiosemicarbazone). Structure, cytotoxic activity and DNA binding of Pd(II)-benzyl bis(thiosemicarbazonate).

The preparation of palladium(II) complexes of 3,5-diacyl-1,2,4-triazole bis(thiosemicarbazone) (H2L2), 2,6-diacylpyridine bis(thiosemicarbazone) (H2L3) and benzyl bis(thiosemicarbazone) (H2L4) is described. The new complexes [PdCl2(H2L2)] (1), [PdCl2(H2L3)] (2) and [PdL4].DMF (3) have been characterized by elemental analyses and spectroscopic studies (IR, 1H NMR and UV-Vis). The crystal and molecular structure of PdL4.DMF (L = bideprotonated form of benzyl bis(thiosemicarbazone)) has been determined by single-crystal X-ray diffraction: green triclinic crystal, a = 10.258(5), b = 10.595(5), c = 11.189(5) A, alpha = 97.820(5), beta = 108.140(5), gamma = 105.283(5) degrees, space group P1, Z = 1. The palladium atom is tetracoordinated by four donor atoms (SNNS) from L4 to form a planar tricyclic ligating system. The testing of the cytotoxic activity of compound 3 against several human, monkey and murine cell lines sensitive (HeLa, Vero and Pam 212) and resistant to cis-DDP (Pam-ras) suggests that compound 3 might be endowed with important antitumor properties since it shows IC50 values in a microM range similar to those of cis-DDP [cis-diamminedichloroplatinum(II)]. Moreover, compound 3 displays notable cytotoxic activity in Pam-ras cells resistant to cis-DDP (IC50 values of 78 microM versus 156 microM, respectively). On the other hand, the analysis of the interaction of this novel Pd-thiosemicarbazone compound with DNA secondary structure by means of circular dichroism spectroscopy indicates that it induces on the double helix conformational changes different from those induced by cis-DDP.

Animals↗
PubMed1999

Characterization of the domains of E. coli initiation factor IF2 responsible for recognition of the ribosome.

We have studied the interactions between the ribosome and the domains of Escherichia coli translation initiation factor 2, using an in vitro ribosomal binding assay with wild-type forms, N- and C-terminal truncated forms of IF2 as well as isolated structural domains. A deletion mutant of the factor consisting of the two N-terminal domains of IF2, binds to both 30S and 50S ribosomal subunits as well as to 70S ribosomes. Furthermore, a truncated form of IF2, lacking the two N-terminal domains, binds to 30S ribosomal subunits in the presence of IF1. In addition, this N-terminal deletion mutant IF2 possess a low but significant affinity for the 70S ribosome which is increased by addition of IF1. The isolated C-terminal domain of IF2 has no intrinsic affinity for the ribosome nor does the deletion of this domain from IF2 affect the ribosomal binding capability of IF2. We conclude that the N-terminus of IF2 is required for optimal interaction of the factor with both 30S and 50S ribosomal subunits. A structural model for the interaction of IF2 with the ribosome is presented.

Binding Sites↗
PubMed1999

Immunochemical determination of cellular content of translation release factor RF4 in Escherichia coli.

The biosynthesis of proteins in prokaryotes is terminated when a stop codon is present in the A-site of the 70S ribosomal complex. Four different translation termination factors are known to participate in the termination process. Release factor RF1 and RF2 are responsible for the recognition of the stop codons, and RF3 is known to accelerate the overall termination process. Release factor RF4 is a protein involved in the release of the mRNA and tRNA from the ribosomal complex. Furthermore, RF4 is involved in the proofreading in the elongation step of protein biosynthesis. The cellular contents of RF1, RF2, and RF3 were determined earlier. Here we report the cellular content of RF4 in Escherichia coli to be approximately 16,500 molecules per cell. The cells were grown in a rich medium and harvested in the beginning of the exponential growth phase. The quantifications were performed by using Western immunoblotting with radioactive iodinated streptavidin and biotinylated rabbit anti-mouse immunoglobulins plus a highly specific monoclonal antibody against RF4 as first antibody.

Animals↗
PubMed1999

Comparison of isoenzyme electrophoresis and morphometric analysis for phylogenetic reconstruction of the Rhodniini (Hemiptera: Reduviidae: Triatominae).

A phylogenetic reconstruction of the medically important tribe Rhodniini (Hemiptera: Reduviidae) based on multilocus isoenzyme electrophoresis is compared with phylogenetic patterns derived from a traditional morphometric analysis. Even with non-normality in the morphometric data, and some inequalities in population variances, discriminant analysis of size-free variables provided broadly similar phylogenetic information to that derived from isoenzyme analysis, revealing 3 main species groups within the genus Rhodnius.

Animals↗
PubMed1998

Binding of Escherichia coli initiation factor IF2 to 30S ribosomal subunits: a functional role for the N-terminus of the factor.

In the initiation step of bacterial protein synthesis initiation factor IF2 has to join the 30S ribosomal subunit in order to promote the binding of the fMet-tRNAMetf. In order to identify regions within IF2 which may be involved in the primary ribosome-factor interaction, we have constructed several C-terminal and N-terminal truncated forms of the factor as well as isolated structural domains, and tested them in a 30S ribosomal binding assay in vitro. Monoclonal antibodies with epitopes located within the two N-terminal domains of IF2 were used in these experiments. Hitherto, no function has been allocated to the N-terminal region of IF2. Here we show that a mutant consisting of the two N-terminal domains has intrinsic affinity to the ribosomal subunit. Furthermore, a deletion mutant of IF2 which is lacking the two N-terminal domains shows negligible affinity. Moreover mAb with epitopes located within domain II strongly inhibits the binding capacity of IF2 to the 30S ribosomal subunit, whereas mAb with epitopes mapped within domain I do not affect the binding of the factor. The C-terminal domain of IF2 shows no affinity for the small ribosomal subunit. In addition, mutants with C-terminal deletions are not significantly affected in this interaction. Therefore, we conclude that the N-terminus of IF2 has affinity per se to bind the ribosomal subunit, with domain II being directly involved in the interaction.

Amino Acid Sequence↗