Biomedical subjects

M A Valenzuela

Publications and source records attributed to M A Valenzuela.

At least 19 recordsLinked to original sources

PubMed2005

Potato tuber isoapyrases: substrate specificity, affinity labeling, and proteolytic susceptibility.

Apyrase/ATP-diphosphohydrolase hydrolyzes di- and triphosphorylated nucleosides in the presence of a bivalent ion with sequential release of orthophosphate. We performed studies of substrate specificity on homogeneous isoapyrases from two potato tuber clonal varieties: Desiree (low ATPase/ADPase ratio) and Pimpernel (high ATPase/ADPase ratio) by measuring the kinetic parameters K(m) and k(cat) on deoxyribonucleotides and fluorescent analogues of ATP and ADP. Both isoapyrases showed a broad specificity towards dATP, dGTP, dTTP, dCTP, thio-dATP, fluorescent nucleotides (MANT-; TNP-; ethene-derivatives of ATP and ADP). The hydrolytic activity on the triphosphorylated compounds was always higher for the Pimpernel apyrase. Modifications either on the base or the ribose moieties did not increase K(m) values, suggesting that the introduction of large groups (MANT- and TNP-) in the ribose does not produce steric hindrance on substrate binding. However, the presence of these bulky groups caused, in general, a reduction in k(cat), indicating an important effect on the catalytic step. Substantial differences were observed between potato apyrases and enzymes from various animal tissues, concerning affinity labeling with azido-nucleotides and FSBA (5'-p-fluorosulfonylbenzoyl adenosine). PLP-nucleotide derivatives were unable to produce inactivation of potato apyrase. The lack of sensitivity of both potato enzymes towards these nucleotide analogues rules out the proximity or adequate orientation of sulfhydryl, hydroxyl or amino-groups to the modifying groups. Both apyrases were different in the proteolytic susceptibility towards trypsin, chymotrypsin and Glu-C.

Affinity Labels↗

PubMed2005

Longitudinal analysis of metalloproteinases, tissue inhibitors of metalloproteinases and clinical parameters in gingival crevicular fluid from periodontitis-affected patients.

BACKGROUND: The aim of this work was to improve the assessment of the periodontal disease status through measurements of extracellular matrix metalloproteinases (MMPs) and their tissular inhibitors (TIMPs) in the gingival crevicular fluid from patients diagnosed with chronic periodontitis. METHODS: Gingival crevicular fluid samples from patients (n = 13) were taken from 60 sites initially, and from 51 and 41 sites, respectively, 3 and 6 months after scaling and root planing. Gingival crevicular fluid samples were also taken from healthy subjects (n = 11, 24 sites). The presence of MMP-9 and MMP-8 was assessed by zymography and immunowestern blotting, respectively. The actual MMP activity (gelatinase and collagenase) was measured using the fluorogenic substrate assay. TIMP-1 and -2 levels were measured by immunodot blot. RESULTS: The fluorogenic substrate assay determinations showed higher MMP activity in sites with probing depth > or = 4 mm, with significant reduction post-treatment. Gelatinase activity followed by zymography consisted mainly of MMP-9. A different pattern of MMP-8 in control and patient sites was found. Controls only showed species of a partially active form (69 kDa), whereas patient sites showed a high frequency of the active form (56 kDa), and in some cases the latent form (85 kDa) was also observed. The active form reduced its frequency in sites with probing depth > or = 4 mm. TIMP-1 and -2 levels in patients were significantly lower than in controls, and after treatment the recovery of TIMP-1 level similar to control was observed. CONCLUSION: Significant correlations between the severity of the periodontal disease and the actual MMP activity, the active form of MMP-8 and the low level of both TIMP-1 and TIMP-2 were found.

Adult↗

PubMed2004

Extracellular matrix protein expression in cerebrospinal fluid from patients with tropical spastic paraparesis associated with HTLV-I and Creutzfeldt-Jakob disease.

The cerebrospinal fluid (CSF) is in direct contact with the extracellular space of the CNS, thus biochemical processes in the CNS could potentially be reflected in the CSF. Changes in extracellular matrix (ECM) proteins can be studied through their analysis in the CSF. ECM plays an essential role in CNS homeostasis and several proteins such as laminin (LN), fibronectin (FN), thrombospondin (TS) and heparan sulphate proteoglycan (HS, perlecan) form part of its structure. Possible changes in the levels of these proteins were investigated in two different pathologies--tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) (n=25) and Creutzfeldt-Jakob disease (CJD) (n=19)--and compared with those in a control group with or without neurological disease (n=25). CSF analyses were carried out using monoclonal or monospecific polyclonal antibodies. In comparison with the control group, it was found that TSP/HAM patients presented significantly higher levels of LN, TS and HS, while in CJD patients the levels of FN, TS and HS were increased. In CJD patients the HS level was almost double that of the TSP/HAM patients. These results suggest a distinct pattern of ECM proteins in CSF in relation to the type of neurological disease. TSP/HAM is a chronic motor disease that affects the white matter of the spinal cord, while CJD is a subacute dementia that affects cerebral neurons and their synapsis.

Adult↗

PubMed2003

Differences in nucleotide-binding site of isoapyrases deduced from tryptophan fluorescence.

Comparative studies of intrinsic and extrinsic fluorescence of apyrases purified from two potato tuber varieties (Pimpernel and Desirée) were performed to determine differences in the microenvironment of the nucleotide binding site. The dissociation constants (K(d)) of Pimpernel apyrase for the binding of different fluorescent substrate analogs: methylanthranoyl (MANT-), trinitrophenyl (TNP-), and epsilon -derivatives of ATP and ADP were determined from the quenching of Trp fluorescence, and compared with K(d) values previously reported for Desirée enzyme. Binding of non-fluorescent substrate analogues decreased the Trp emission of both isoapyrases, indicating conformational changes in the vicinity of these residues. Similar effect was observed with fluorescent derivatives where, in the quenching effect, the transfer of energy from tryptophan residues to the fluorophore moiety could be additionally involved. The existence of energy transfer between Trp residues in the Pimpernel enzyme was demonstrated with epsilon -analogues, similar to our previous observations with the Desirée. From these results we deduced that tryptophan residues are close to or in the nucleotide binding site in both enzymes. Experiments with quenchers like acrylamide, Cs(+) and I(-), both in the presence and absence of nucleotide analogues, suggest the existence of differences in the nucleotide binding site of the two enzymes. From the results obtained in this work, we can conclude that the differences found in the microenvironment of the nucleotide binding site can explain, at least in part, the kinetic behaviour of both isoenzymes.

Acrylamide↗

PubMed2002

ATPase and Adpase activities in synovial membrane of equine metacarpophalangeal joint.

ATPase and ADPase activities capable of hydrolyzing nucleoside di- and triphosphates in the presence of Ca2+ are present in synovial membrane of metacarpophalangeal joint mainly associated to membrane fractions. These hydrolytic activities have been considered involved in the inflammatory process where ATP and ADP are inflammatory mediators while adenosine counteracts this effect. Both, subcellular localization and kinetic properties of these nucleotidase activities, suggest that could correspond to single enzyme called ATP-diphosphohydrolase or apyrase. The comparison of the activity on ATP-Ca and ADP-Ca from normal and pathological equine synovial membrane did not show significant differences either in the subcellular fraction distribution or in the enrichment of each subcellular fraction. Neither differences on 5'-nucleotidase activity present in the microsomal fraction were observed.

5'-Nucleotidase↗

PubMed2001

Nitric oxide synthase activity in brain tissues from llama fetuses submitted to hypoxemia.

The fetal llama (Lama glama; a species adapted to live in chronic hypoxia in the highlands of the Andes) did not increase cerebral blood flow and reduce the brain oxygen uptake during hypoxemia. Although nitric oxide (NO) is a normal mediator in the regulation of vascular tone and synaptic transmission, NO overproduction by hypoxemia could produce neuronal damage. We hypothesized that nitric oxide synthase (NOS) activity is either maintained or reduced in the central nervous system of the llama fetuses submitted to chronic hypoxemia. Approximately 85% of the Ca(2+)-dependent NOS activity was soluble, at least 12% was associated with the mitochondrial fraction, and less than 5% remains associated with microsomes. To understand the role of NO in chronic hypoxemia, we determined the effect of 24-h hypoxemia on NOS activity in the central nervous system. No changes in activity or the subcellular distribution of NOS activity in brain tissues after hypoxemia were found. We proposed that the lack of changes in NOS activity in the llama under hypoxemia could be a cytoprotective mechanism inherent to the llama, against possible toxic effects of NO.

Animals↗

PubMed2001

[Radioguided surgery of hyperparathyroidism. A case report].

Primary hyperparathyroidism is the main cause of hypercalcemia in ambulatory patients. Classic surgical resolution of this disease includes bilateral cervical exploration with exhibition of the four parathyroid glands and evaluation of the suspicious gland with a rapid biopsy. We report a 79 years old female with a primary hyperparathyroidism in whom the adenoma causing the disease was located with the help of an intraoperative gamma-probe that detected the zone of higher radiation counting of Tc99m Sestamibi, that was injected preoperatively. The patient was discharged with normal serum calcium and phosphate levels.

Adenoma↗

PubMed2001

[Risk factors for morbidity and mortality in patients with essential hypertension, followed for 25 years].

BACKGROUND: Among hypertensive patients, other risk factors for mortality and morbidity, besides blood pressure, must be considered when therapeutic decisions are done. AIM: To assess the incidence and relevance of cardiovascular risk factors in a cohort of patients with essential hypertension. MATERIAL AND METHODS: A cohort of 1,072 treated patients with essential hypertension was followed for a period up to 25 years. Four hundred eighty six were men and 586 were women, age ranged from 31 to 70 years. At entry, 56% of subjects did not have any organic complications associated to hypertension (stage I WHO criteria), 30% had mild alterations (Stage II) and 14% had major complications (myocardial infarction, stroke, heart failure or renal failure). Likewise, 43.8% had mild, 14.5%, moderate and 41.7%, severe hypertension. Patients were treated with monotherapy or combined therapy based on diuretics, beta blockers, calcium antagonists and angiotensin converting enzyme inhibitors. Goal of therapy was 140/90 mm Hg. Risk factors associated diseases and complications were registered carefully. Causes of death were obtained from hospital records and death certificates. Mortality was analyzed using life tables (intention to treat method included). RESULTS: Blood pressure dropped significantly during follow up from a mean of 182/110 to 154/92 mm Hg. During follow up, 143 patients died and 429 complications (lethal or non lethal) were recorded. Twenty four percent of patients smoked, 24% reported alcohol intake, 56% had hypercholesterolemia, 11% were obese, 13% had diabetes and 3% had gout. The proportional hazard model showed that the existence of previous complications, the presence of more than 3 risk factors, and age over 60 and mean systolic and diastolic pressure during therapy, were independent and significant risk factors for mortality. CONCLUSIONS: The incidence of risk factors among our hypertensive patients is very similar to that of other national or international cohorts.

Adult↗

PubMed2000

Fluorescence studies of ATP-diphosphohydrolase from Solanum tuberosum var. Desirée.

Chemical modification of potato apyrase suggests that tryptophan residues are close to the nucleotide binding site. Kd values (+/- Ca2+) for the complexes of apyrase with the non-hydrolysable phosphonate adenine nucleotide analogues, adenosine 5'-(beta,gamma-methylene) triphosphate and adenosine 5'-(alpha,beta-methylene) diphosphate, were obtained from quenching of the intrinsic enzyme fluorescence. Other fluorescent nucleotide analogues (2'(3')-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate, 2'(3')-O-(2,4,6-trinitrophenyl) adenosine 5'-diphosphate. 1,N6-ethenoadenosine triphosphate and 1,N6-ethenoadenosine diphosphate) were hydrolysed by apyrase in the presence of Ca2+, indicating binding to the active site. The dissociation constants for the binding of these analogues were calculated from both the decrease of the protein (tryptophan) fluorescence and enhancement of the nucleotide fluorescence. Using the sensitised acceptor (nucleotide analogue) fluorescence method, energy transfer was observed between enzyme tryptophans and ethene-derivatives. These results support the view that tryptophan residues are present in the nucleotide-binding region of the protein, appropriately oriented to allow the energy transfer process to occur.

Adenine Nucleotides↗

PubMed2000

Effect of protein-modifying reagents on ecto-apyrase from rat brain.

We have tested several chemical modifiers to investigate which amino acid residues, present in the primary structure of the ecto-apyrase, could be involved in catalysis. Synaptosomes from cerebral cortex of rats were prepared and the ATP diphosphohydrolase activity was assayed in absence or the presence of the modifiers. Percentages of residual activity for ATPase and ADPase obtained when the following reagents were tested, are respectively: phenylglyoxal (an arginine group modifier) 17 and 30%; Woodward's reagent (a carboxylic group modifier) 33 and 23%; Koshland's reagent (a tryptophan group modifier) 10 and 12%; maleic anhidride (an amino group modifier) 11 and 25% and carbodiimide reagent (a carboxylic group modifier) 56 and 72%. Otherwise, PMSF, a seryl protein modifier and DTNB, a SH-group modifier did not affect either ATPase or ADPase activity. Inhibitions observed after treatment with phenylglyoxal and Woodward's reagent were significantly prevented when the synaptosomal fraction was preincubated with ATP and ADP, indicating that the arginine and the side chain of glutamate or aspartate (carboxyl groups) participate in the structure of the active site. This interpretation was confirmed by using GTP and GDP, two other apyrase substrates. Phenylglyoxal and Woodward's reagent also inhibited the GTPase and GDPase activities and this inhibition was prevented by preincubation with these substrates.

2-Hydroxy-5-nitrobenzyl Bromide↗

PubMed2000

Studies on ATP-diphosphohydrolase nucleotide-binding sites by intrinsic fluorescence.

Potato apyrase, a soluble ATP-diphosphohydrolase, was purified to homogeneity from several clonal varieties of Solanum tuberosum. Depending on the source of the enzyme, differences in kinetic and physicochemical properties have been described, which cannot be explained by the amino acid residues present in the active site. In order to understand the different kinetic behavior of the Pimpernel (ATPase/ADPase = 10) and Desirée (ATPase/ADPase = 1) isoenzymes, the nucleotide-binding site of these apyrases was explored using the intrinsic fluorescence of tryptophan. The intrinsic fluorescence of the two apyrases was slightly different. The maximum emission wavelengths of the Desirée and Pimpernel enzymes were 336 and 340 nm, respectively, suggesting small differences in the microenvironment of Trp residues. The Pimpernel enzyme emitted more fluorescence than the Desirée apyrase at the same concentration although both enzymes have the same number of Trp residues. The binding of the nonhydrolyzable substrate analogs decreased the fluorescence emission of both apyrases, indicating the presence of conformational changes in the neighborhood of Trp residues. Experiments with quenchers of different polarities, such as acrylamide, Cs+ and I- indicated the existence of differences in the nucleotide-binding site, as further shown by quenching experiments in the presence of nonhydrolyzable substrate analogs. Differences in the nucleotide-binding site may explain, at least in part, the kinetic differences of the Pimpernel and Desirée isoapyrases.

Adenosine Diphosphate↗

PubMed2000

[Increased activity of metalloproteinases and their inhibitors in cerebrospinal fluid of patients with tropical spastic paraparesis].

BACKGROUND: Proteolytic modifications of neuronal surfaces and the surrounding extracellular matrix are very important in neuronal development and regeneration. Increased activity of matrix metalloproteinases (MMPs) and their tissue inhibitors, due to secretion by macrophages and lymphocytes, occur in inflammatory processes that disrupt the blood brain barrier. However, neurons and microglia can also secrete these enzymes. AIM: To identify the type of MMP present in the cerebrospinal fluid (CSF) and changes in the expression of tissue inhibitors of metalloproteinases (TIMPs) in patients with HTLV-1 associated tropical spastic paraparesis. PATIENTS AND METHODS: CSF samples from 12 patients with HTLV-1 associated tropical spastic paraparesis and 12 healthy controls were obtained by an atraumatic lumbar puncture. The presence of MMPs was measured by zymography and the relative amounts of TIMPs were measured by immunowestern blot. RESULTS: In the CSF of both controls and patients, a similar gelatinolytic band corresponding to proMMP-2 (latent form) was observed. In 83.3% of patients with HTLV 1 associated tropical spastic paraparesis, the MMP-9 was also present. TIMP-1, TIMP-2 and TIMP-3 were elevated 2.24 +/- 0.72, 3.85 +/- 1.38 and 5.89 +/- 3.4 fold, respectively, in the CSF of patients as compared to controls. CONCLUSIONS: Patients with HTLV-1 associated tropical spastic paraparesis have elevated activity of MMP-9 and levels of TIMPs in the CSF, when compared to healthy controls.

Adult↗

PubMed1999

Gelatinase activity of matrix metalloproteinases in the cerebrospinal fluid of various patient populations.

We have studied the enzymatic gelatinolytic activity of matrix metalloproteinases (MMPs) present in cerebrospinal fluid (CSF) of samples obtained from 67 individuals, twenty-one nonneurological patients (considered controls) and 46 subjects with various neurological disorders e.g., vascular lesions, demyelination, inflammatory, degenerative and prion diseases. Biochemical characterization of MMPs, a family of neutral proteolytic enzymes involved in extracellular matrix modeling, included determination of substrate specificity and Ca+2 dependency, as well as the effects of protease inactivators, carboxylic and His (histidine) residue modifiers, and antibiotics. Whereas all CSF samples expressed MMP-2 (gelatinase A) activity, it corresponded in most cases (normal and pathological samples) to its latent form (proenzyme; pMMP-2). In general, inflammatory neurological diseases (especially meningitis and neurocisticercosis) were associated with the presence of a second enzyme, MMP-9 (or gelatinase B). Whereas MMP-9 was found in the CSF of every tropical spastic paraparesis patient studied, its presence in samples from individuals with vascular lesions was uncommon. Patients blood-brain barrier damage was ascertained by determining total CSF protein content using both, the conventional polyacrylamide gel electrophoresis procedure under denaturing conditions and capillary zone electrophoresis.

Enzyme Activation↗

PubMed1998

Porque me tocó a mi? Mexican American diabetes patients' causal stories and their relationship to treatment behaviors.

This paper reports findings from an ethnographic study of self-care behaviors and illness concepts among Mexican-American non-insulin dependent diabetes mellitus (NIDDM) patients. Open-ended interviews were conducted with 49 NIDDM patients from two public hospital outpatient clinics in South Texas. They are self-identified Mexican-Americans who have had NIDDM for at least 1 yr, and have no major impairment due to NIDDM. Interviews focused on their concepts and experiences in managing their illness and their self-care behaviors. Clinical assessment of their glucose control was also extracted from their medical records. The texts of patient interviews were content analyzed through building and refining thematic matrixes focusing on their causal explanations and treatment behaviors. We found patients' causal explanations of their illness often are driven by an effort to connect the illness in a direct and specific way to their personal history and their past experience with treatments. While most cite biomedically accepted causes such as heredity and diet, they elaborate these concepts into personally relevant constructs by citing Provoking Factors, such as behaviors or events. Their causal models are thus both specific to their personal history and consistent with their experiences with treatment success or failure. Based on these findings, we raise a critique of the Locus of Control Model of treatment behavior prevalent in the diabetes education literature. Our analysis suggests that a sense that one's own behavior is important to the disease onset may reflect patients' evaluation of their experience with treatment outcomes, rather than determining their level of activity in treatment.

Adaptation, Psychological↗

PubMed1997

Kinetic characteristics of nucleoside mono-, di- and triphosphatase activities of the periplasmic 5'-nucleotidase of Escherichia coli.

Periplasmic 5'-nucleotidase from Escherichia coli, in addition to the monophosphoesterase activity has a diphosphohydrolase activity, acting on nucleoside di- and triphosphates. We proposed that the monophosphoesterase and diphosphohydrolase activities have their own active site. This proposal is based on the different types of bonds being broken. Chemical modification with selective group reagents did not show differences in the essentiality of some residues, like histidyl, carboxyl and arginyl groups, of these two hydrolytic activities. While kinetic approaches employing the competition plot and unidirectional substrate inhibition point to that diphosphohydrolase activity (ATPase-ADPase) do not share the same active site with monophosphoesterase activity. Western blotting developed with polyclonal anti-placental apyrase antibody revealed a single protein in the periplasmic fraction of 66.5 kDa similar to the Mr of the purified enzyme by isoelectrofocusing.

5'-Nucleotidase↗

PubMed1997

NIDDM patients' fears and hopes about insulin therapy. The basis of patient reluctance.

OBJECTIVE: This study examines NIDDM patients' attitudes toward insulin injections, the basis of these attitudes, and how they may affect patients' willingness to take insulin. RESEARCH DESIGN AND METHODS: Forty-four low-income Mexican American NIDDM patients were interviewed using open-ended in-depth interviewing techniques. Transcripts were analyzed using techniques of content analysis. Data classification was cross-checked in analysis conferences and through a second researcher coding 50% of the cases, comparing the results, then resolving any discrepancies. RESULTS: Patients' positive attitudes toward insulin focus on its efficacy and efficiency, the avoidance of complications, and feeling better and more energetic. Negative attitudes were much more frequently discussed and include "technical concerns": anxiety about the pain, proper techniques, and general hassles of taking injections; about hypoglycemic symptoms; and about insulin causing serious health problems; and "experimental concerns": sensing that the disease has progressed into a serious phase, that past treatment efforts have failed, and that the patient has not taken proper care. Attitudes were based on personal experience, observation, what others say, and interactions with health care professionals. CONCLUSIONS: Results from the few published reports on NIDDM patients' attitudes about insulin from various cultural settings were consistent with our findings, indicating that these themes may be generally applicable to a wider population. It is recommended that health care providers take care to avoid unwitting promotion of negative attitudes toward insulin and actively elicit and respond to patient attitudes to reduce reluctance to take the medication.

Adult↗

PubMed1997

Human placental ecto-enzymes: studies on the plasma membrane anchorage and effect of inhibitors of ATP-metabolizing enzymes.

The human placental microvillar membrane contains several ectoenzymes, including 5'-nucleotidase, alkaline phosphatase and ATP-diphosphohydrolase (ATP-DPH), which might be involved in the extracellular metabolism of nucleotides. The type of anchorage to the plasma membrane of the two first enzymes has been shown to be via a glycosyl-phosphatidylinositol. In the present study, using an enzymatic approach, we show that the ATP-DPH should be attached to the plasma membrane through a different type of anchorage. We were also interested in the search of compounds which could interact differentially with this enzyme to be used as a tool for studying the other two hydrolytic enzymes in the presence of ATP-DPH. Here we report several inhibitors of ecto-ATPases which seem to be a useful tool for studying these three enzymes.

5'-Nucleotidase↗

PubMed1996

Partial purification and immunohistochemical localization of ATP diphosphohydrolase from Schistosoma mansoni. Immunological cross-reactivities with potato apyrase and Toxoplasma gondii nucleoside triphosphate hydrolase.

ATP diphosphohydrolase from tegumental membranes of Schistosoma mansoni was solubilized with Triton X-100 plus deoxycholate and separated by preparative nondenaturing polyacrylamide gel electrophoresis. Two isoforms with ATP-hydrolytic activity were identified and excised from nondenaturing gels. For each of the active bands, two protein bands (63 and 55 kDa) were detected with Coomassie Blue staining, following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Western blots developed with polyclonal anti-potato apyrase antibody revealed a single protein of 63 kDa, either with samples excised from active bands or with total S. mansoni tegument. Anti-potato apyrase antibody immobilized on Sepharose-Protein A depleted over 95% of ATPase and ADPase activities from detergent-solubilized tegument. Confocal laser scanning microscopy showed anti-potato apyrase antibody on the outer surface of S. mansoni tegument. A different antibody against a fusion protein derived from recently cloned Toxoplasma gondii nucleoside triphosphate hydrolase (Bermudes, D., Peck, K. R., Afifi, M. A., Beckers, C. J. M., and Joiner, K. A. (1994) J. Biol. Chem. 269, 29252-29260) revealed the same 63-kDa band in Western blots of S. mansoni tegument. Since anti-potato apyrase antibodies exhibited cross-reactivity with S. mansoni ATP diphosphohydrolase, we decided to gain further information on the primary structure of potato apyrase by sequencing the protein. Three novel peptides were obtained: amino-terminal sequence and two internal sequences from tryptic fragments. Eight sequences recently deposited in the data bank, including that of T. gondii nucleoside triphosphate hydrolase, have considerable homologies to potato apyrase suggesting a new family of nucleoside triphosphatases which contains a conserved motif (I/V)(V/M/I)(I/L/F/C)DAGS(S/T) near the amino-terminal. Antibody cross-reactivities in the present work suggest that conserved epitopes from S. mansoni ATP diphosphohydrolase are present in this family of nucleotide-splitting enzymes.

Acid Anhydride Hydrolases↗