Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-Acetyl-L-phenylalanine inhibition of the peptic hydrolysis of N-acetyl-L-phenylalanine-L-tyrosine over the pH range 2-4.5 was studied. The mixed character of inhibition which was partially competitive and partially non-competitive allowed us to infer that the separate steps of the enzymatic hydrolysis were pH dependent. The orderliness of the dissociation of the triple enzyme-product-product complex was also pH dependent. The group with pKa approximately 3 influenced the mechanisms of pepsin hydrolysis as strongly as in the case of pepsin catalyzed oxygen isotopic exchange in the acyl amino acid carboxyl group.
Mol Biol (Mosk)
PMID:[pH-dependence of the mechanism of pepsin action]. 0 63

Parameters of rotational relaxation of pepsin conjugated in neutral and slightly alkaline solutions with a fluorescent label 1-dimethylaminonaphthalene-5-sulphonyl chloride (DNS-Cl) are measured by a fluorescence polarization method. It is shown that the globule of pepsin denatured and loose at lakaline pH values converts into a compact form after transfer to acidic solution. The compactness of this new form is close to that of native inhibited pepsin. A new globule is distinguished from the native by the absence of segmental flexibility. Conjugated with a DNS at pH less than or equal to 7.0 pepsin relaxes in solution as catalytically active dansylated aminopepsin (DNS-3-aminotyrosine pepsin). Evidence is presented that these conjugates are also characterized by segmental flexibility.
Mol Biol (Mosk)
PMID:[The fluorescence of pepsin conjugates with DNS-chloride]. 0 44

1. The properties of inactive and active renin in human plasma and amniotic fluid were studied chromatographically. Activation was achieved at pH 3.3 with and without added pepsin. 2. Acid activation of renin was time- and temperature-dependent but was inhibited by dilution of the sample. The dilution effect was corrected by adding pepsin. Such characteristics indicate that activation at low pH is catalysed by intrinsic enzymes. 3. Separation and/or dilution of the activating enzyme during ion-exchange chromatography concealed the eluted position of inactive renin and reduced the amount recovered. Only after full activation of the eluted renin was achieved with added pepsin was a distinct peak of inactive renin exposed. 4. At pH 7.5 inactive renin carried a lower negative charge than the active enzyme. This charge difference was lost after activation. 5. No molecular-weight differences between active, inactive renin or the International Renin Standard were detected by gel filtration. No renin of larger molecular weight was present. 6. These findings will be helpful in purification studies of human inactive renin.
Clin Sci Mol Med 1978 Jul
PMID:The nature of inactive renin in human plasma and amniotic fluid. 2 28

In connection with a hypothesis of segmental flexibility of pepsin and its derivative aminopepsin (containing 3-aminotyrosine residues), a dynamic behaviour of pepsin and dansylated aminopepsin in aqueous solutions at pH 1.0--8.3 in investigated. It is shown that a dynamic structure of pepsin at pH 2.5--6.0 is almost invariant and very close to a structure studied in detail at pH 5.5. The lowering of a solution pH value from 2.5 to 1.0 is accompanied by labilization of pepsin and dansylated aminopepsin structures. Denaturation phenomena after thermal treatment of dansylated aminopepsin are also studied. An incubation of the latter in 0.1 M acetate buffer at pH 5.5 and temperature 50--80 degrees C with a subsequent cooling leads to irreversible conformational changes. The character of these changes is essentially dependent upon the incubation conditions.
Mol Biol (Mosk)
PMID:[Influence of pH and thermal treatment on the intramolecular mobility of pepsin]. 3 50

1. Eight cyclo-alkyl lactamimides have been investigated for potential inhibitory action upon the pepsins and pepsinogens. 2. Human pepsins 1, 3 and 5 and swine pepsin were inhibited only slightly. 2. Human and swine pepsinogens were inactivated progressively by lactamimides as the number of methylene groups in the nitrogen-containing ring increased. The most potent inactivator studied was N-(cis-2-phenylcyclopentyl)-azacyclotridecan-2-imine hydrochloride. 4. Substitution of benzyl and tertiary butyl groups in the N-containing ring increased the pepsinogen-inactivating property of the cyclo-alkyl lactamimides. 5. N-(cis-2-Phenylcyclopentyl)azacyclotridecan-2-imine hydrochloride may be of potential importance as a therapeutic agent in peptic ulcer, and modifications to the molecule which might increase its pepsinogen-inactivating ability are suggested.
Clin Sci Mol Med 1978 Feb
PMID:Effect of cyclo-alkyl lactamimides upon human pepsins and pepsinogens. 34 Jan 16

A detailed description of structural investigations of pepsin from 3.5 to 2.7 A resolution are given. The main attention is drawn to the conformation of the polypeptide backbone of the enzyme. The numbers of amino acid residues involved in the formation of various structural elements are listed. The structure of pepsin is similar to that of acid proteases isolated from lower organisms. The two domain structure of all acid proteases has a periodicity in the sequence of beta-segments and helices and a very specific symmetrical structure of each domain. This makes it possible to describe the structure of acid proteases in simple terms.
Mol Biol (Mosk)
PMID:[X-ray structural analysis of pepsin. V. Conformation of the main chain of the enzyme]. 35 68

Thermal transitions in pepsin crystals were studied by scanning microcalorimetry and microscopy. A sharp dependence of thermal transition parameters upon the heating rate was discovered. It was determined that during the heating of pepsin crystals it is possible to observe phase transition of the first order type. Thermal transition is connected only with the denaturation of protein molecules in the crystal. The absence of crystals melting was shown with the help of microscopy. The coincidence of equilibrium denaturation temperatures of pepsin in crystal and in solution was shown in direct calorimetric experiments. The results obtained point to the fact that intermolecular interactions do not give any contribution to the thermostability of hydrated supermolecular protein systems.
Mol Biol (Mosk)
PMID:[Thermal denaturation of pepsin in crystal form and in solution]. 36 2

By modifying four tyrosine residues in pepsin a derivative (aminopepsin) is obtained which is capable to conjugate with a fluorescent label DNS-Cl without loss of the catalytic activity. Rotational relaxation times of native pepsin and dansylated aminopepsin (DAP) are measured by a fluoresence polarization method. The values obtained are shown to be lower than those calculated for arigid pepsin globule. Possible sources of the obtained difference are discussed. A reversible or covalent blocking of pepsin or DAP active centres by specific inhibitors leads to an increase in rotational relaxation time values for these proteins reaching the magnitude which is very close to that calculated for a model of rigid pepsin. Brownian relaxation of pepsin and DAP reduced by beta-mercaptoethanol and of pepsinogen and some fragments of pepsine macromolecule in aqueous solutions is invigated as well. The results are intepreted as representing an intramolecular mobility or segmental flexibility of pepsin and DAP. With the use of the obtained and X-ray data a segmental model of dynamic pepsin structure is suggested. On the basis of this model some conclusions are drawn concerning a localization of a polypeptide which is split off from the N-terminus of pepsinogen during its activation. A possible role of segmental flexibility in the catalytic action of pepsin is considered.
Mol Biol (Mosk)
PMID:[Intramolecular mobility of pepsin]. 78 36

The heavy water (D2O) has been shown to induce the conformational transitions in trypsin, chymotrypsin and pepsin. The transfer of proteins from H2O into D2O results a change in their sensitivity to UV-light. An increase in sensitivity to the irradiation at 248 nm and a decrease in sensitivity to the irradiation at 280 nm were observed. The quantum yield of chromophore photolysis (for cystyne and tryptophan) is correspondingly changed. However, although the quantum yield of sensitized reduction of cystine by solvated electrons photochemically ejected from the aromatic acid residues during irradiation at 280 nm increases instead of a rise a drop in the quantum yield of protein inactivation is registered. The data obtained are discussed in terms of importance of solvated shell for conformational stability of proteins. The solvated electrons are suggested to be transfered mainly to nonessential disulfide bridges within trypsin molecule. Rupture of these bonds does not result in trypsin inactivation.
Mol Biol (Mosk)
PMID:[Influence of heavy water (D20) on the conformation and UV-sensitivity of proteins]. 80 85

1. Gastric juice was collected at regular intervals during electrical stimulation of the vagus in anaesthetized cats and during insulin hypoglycaemia in both anaesthetized and conscious cats. The total amounts of acid and pepsin secreted were similar in the three groups. 2. Pepsins were examined by agar-gel electrophoresis. Resting juice contained two pepsins, and up to nine pepsins could be detected after stimulation. Three patterns of pepsin secretion were found. 3. The most noticeable feature was the variation in the proportion of total pepsin attributable to the pepsin which migrated most rapidly during electrophoresis (pepsin 1). In response to insulin hypoglycaemia, anaesthetized cats secreted only a small proportion of total pepsin 1 and conscious cats secreted a large proportion as pepsin 1. During direct electrical stimulation of the vagus, the proportion of pepsin 1 rose. 4. The possibility of a dependence of pepsin 1 secretion on vagal stimulation is discussed and the relevance of this to peptic ulcer and to vagotomy is considered.
Clin Sci Mol Med 1975 Apr
PMID:Variation in the proportions of individual pepsins secreted by the cat in response to vagal stimulation and hypoglycaemia. 109 18


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