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)

The paper is a brief account of aspartic proteinases' structural studies developed in V.A. Engelhardt Institute of Molecular Biology during the last 3 years. The work on porcine pepsin has been finalized after the refinement of the monoclinic crystal form at 1.8 A resolution performed in collaboration with the group of protein structure and function studies of the University of Alberta in Canada. An important structural property of chymosin which explains the enzyme specificity has been found. Protein engineering work on chymosin is being developed. The structural template for aspartic proteinases has been elucidated and on the basis of this template the model of HIV-1 protease molecule has been built. Some approaches to the design of HIV-1 protease inhibitors were elucidated.
Mol Biol (Mosk)
PMID:[Various aspects of structural studies of aspartate proteinases]. 269 93

We report a method of sex chromatin analysis of lymphocytes separated from host organs in transfusion-associated graft-versus-host disease (GVHD), which enabled the demonstration of invasion by donor lymphocytes. The lymphocytes examined were separated from deparaffinized tissue blocks of skin, spleen and bone marrow from two female patients with transfusion-associated GVHD by incubation in 0.5% pepsin. The tissues had been removed at autopsy and fixed in formalin. Sex chromatin analysis was performed by fluorescence microscopy on separated lymphocytes stained with 0.005% quinacrine dihydrochloride. By this means Y chromatin-positive (i.e. male) lymphocytes were demonstrated in the skin, spleen and bone marrow of both female patients.
Virchows Arch B Cell Pathol Incl Mol Pathol 1988
PMID:Sex chromatin analysis of lymphocytes invading host organs in transfusion-associated graft-versus-host disease. 290 May 76

The proteinase A structural gene of Saccharomyces cerevisiae was cloned by using an immunological screening procedure that allows detection of yeast cells which are aberrantly secreting vacuolar proteins (J. H. Rothman, C. P. Hunter, L. A. Valls, and T. H. Stevens, Proc. Natl. Acad. Sci. USA, 83:3248-3252, 1986). A second cloned gene was obtained on a multicopy plasmid by complementation of a pep4-3 mutation. The nucleotide sequences of these two genes were determined independently and were found to be identical. The predicted amino acid sequence of the cloned gene suggests that proteinase A is synthesized as a 405-amino-acid precursor which is proteolytically converted to the 329-amino-acid mature enzyme. Proteinase A shows substantial homology to mammalian aspartyl proteases, such as pepsin, renin, and cathepsin D. The similarities may reflect not only analogous functions but also similar processing and intracellular targeting mechanisms for the two proteins. The cloned proteinase A structural gene, even when it is carried on a single-copy plasmid, complements the deficiency in several vacuolar hydrolase activities that is observed in a pep4 mutant. A strain carrying a deletion in the genomic copy of the gene fails to complement a pep4 mutant of the opposite mating type. Genetic linkage data demonstrate that integrated copies of the cloned proteinase A structural gene map to the PEP4 locus. Thus, the PEP4 gene encodes a vacuolar aspartyl protease, proteinase A, that is required for the in vivo processing of a number of vacuolar zymogens.
Mol Cell Biol 1986 Jul
PMID:PEP4 gene of Saccharomyces cerevisiae encodes proteinase A, a vacuolar enzyme required for processing of vacuolar precursors. 302 36

Pepsinogens (PGA) are the inactive precursors of pepsin, the major acid protease found in the stomach. Highly polymorphic variation of these proteins has been demonstrated in several populations, and comparison of the DNA restriction fragment patterns obtained from informative pepsinogen phenotypes suggest that the polymorphism results from chromosomal haplotypes containing variable numbers of pepsinogen genes. In order to isolate the three most common PGA haplotypes (A, B, and C) and to unambiguously demonstrate their relationship to the observed protein heterogeneity, we constructed mouse X human somatic cell hybrids from individuals heterozygous for PGA and INS (insulin). Here, we describe analysis of hybrid cell lines that segregated human chromosomes containing the PGA genes and thereby provided for the parasexual discrimination of the different haplotypes on chromosome 11 determining the corresponding heterozygous phenotypes. These studies demonstrate that the A, B, and C haplotypes contain three, two, and one PGA genes, respectively. This unusual polymorphism of genomic DNA encoding very similar proteins probably reflects recent evolution by gene duplication.
Somat Cell Mol Genet 1987 Mar
PMID:Parasexual analysis of human pepsinogen molecular heterogeneity. 303 27

In order to clarify the mechanism of interaction of serum amyloid P component (SAP) with complement, the interaction of SAP with C1q and with IgG was studied. It is known that SAP binds Sepharose in the presence of calcium. When purified 125I-C1q was incubated with SAP prior to Sepharose affinity chromatography, 125I-C1q was retained. However, in the absence of SAP, the 125I-C1q was not retained. To further examine the interaction of SAP with C1q, isolated SAP was incubated at varying ratios with C1q in the presence of 1.5 mM Ca2+. These mixtures were subsequently examined via crossed immunoelectrophoresis against goat anti-SAP. A change in the electrophoretic behavior of SAP was observed in the presence of C1q. In other studies, it was observed that SAP might interact with the collagen-like stem of C1q. In these latter studies, 125I-SAP was incubated with pepsin digests of C1q in a microtitre solid-phase binding assay. In addition, a microtitre solid-phase binding assay was utilized in order to investigate the possible binding of isolated 125I-SAP with IgG. Interestingly in the presence of Ca2+, human IgG and Fab gamma, but not Fc gamma, were found to bind 125I-SAP.
Mol Immunol 1986 Oct
PMID:Evidence for the binding of human serum amyloid P component to Clq and Fab gamma. 309 75

Precipitating and non-precipitating pig anti-2,4-dinitrophenyl group (Dnp) antibodies were investigated by differential adiabatic scanning microcalorimetry in the pH range 3.7-4.5. The partial heat capacity functions obtained revealed a notable difference between the two antibody types when the analysis was done at pH 4.5 or 4.0. The transition observed at temps around 50 degrees C in a non-precipitating antibody was absent in a precipitating antibody. Under analogous conditions, pH 4.5, the precipitating antibody was fully resistant to pepsin, while the non-precipitating antibody yielded appropriate F(ab')2 and pFc'fragments. At pH 3.7 no substantial difference in the partial heat capacity function could be observed between the two antibody types. Below pH 4.0 the precipitating antibody became susceptible to peptic cleavage and yielded fragments of the same general character as the non-precipitating antibody. This finding lends support to the view that the structural block in immunoglobulin G that melts first, i.e. at temps near 50 degrees C, is the CH2 domain or a part of it.
Mol Immunol 1986 Jul
PMID:Correlation of the character of intramolecular melting with digestibility by pepsin in precipitating and non-precipitating pig anti-Dnp antibodies. 309 79

The major product of digestion of bovine IgG2a(A1) with immobilized pepsin is F(ab')2 while similar treatment of IgG2a(A2) yields Fab, Fc and other products. It is postulated that structural differences in the hinge region, including the absence of the most N-terminal disulfide bridge in IgG2a(A2) and a displacement of the primary pepsin cleavage site toward the Fd, can explain this effect. The immunodominant A1 allotope(s) appears to be located in the CH3 domain of IgG2a(A1) while the A2 allotopes are located elsewhere and are apparently affected by digestion. The allotypic bias of rabbit anti-IgG2a is also present in anti-IgG2a raised in goats. However, the A2 allotypic determinants of bovine IgG2a are recognized by goat precipitins although precipitins of this specificity are not detectable in rabbits immunized with IgG2a(A2). Rabbit anti-A2 antibodies are detectable using the ELISA in rabbits immunized with IgG2a(A2).
Mol Immunol 1987 Dec
PMID:The heterogeneity of bovine IgG2--IV. Structural differences between IgG2a molecules of the A1 and A2 allotypes. 312 20

We have analyzed the binding of IgG and fragments of IgG [Fc, F(ab')2, and Fab] to group C and G streptococci and to protein G, the IgG binding cell wall protein of these bacteria. A direct correlation (r = 0.87, P less than 0.0001) was observed when the binding of radiolabelled, polyclonal IgG F(ab')2- and Fc-fragments to 23 group C and G streptococcal strains was compared. One strain (G-148) was treated with increasing amounts of pepsin, trypsin or papain and the Fab-binding structure was found to be much more sensitive to the enzymes as compared to the Fc-binding. A 35 K fragment of protein G was coupled to Sepharose, and both radiolabelled IgG F(ab')2- and Fc-fragments bound to the Sepharose beads. Binding of IgG fragments was inhibited by intact IgG or by the homologous IgG fragment, whereas Fc-fragments did not inhibit Fab binding or vice versa. Two radiolabelled protein G-fragments (28 and 35 K) showed different binding to polyclonal IgG, IgG F(ab')2-, IgG Fab- and IgG Fc-fragments. Thus, in a dot binding assay the 35 K fragment bound all IgG fragments tested, whereas the 28 K protein G fragment bound only intact IgG and IgG Fc-fragments. These results indicate two independent and separate binding sites for Fab- and Fc-fragments on protein G. Different binding sites on protein G were also indicated by Western blot analysis of four different protein G-fragments (28, 35, 42 and 65 K). In these experiments the 28 K fragment showed affinity only for Fc-fragments, while the higher mol. wt protein G preparations bound both IgG Fab- and Fc-fragments.
Mol Immunol 1988 Feb
PMID:Streptococcal protein G has affinity for both Fab- and Fc-fragments of human IgG. 313 64

The possibility that pig pepsin has a cation binding specificity in its secondary binding subsites has been examined by the pepsin-catalyzed hydrolysis of a series of synthetic octa- to undecapeptide substrates. These chromophoric substrates are cleaved by pepsin in the phenylalanyl-p-nitrophenylalanyl (Phe-Nph) bond. Lys and Arg residues were placed into seven different positions in the substrates, and their effect on kcat and Km was examined between pH 2.8 and pH 5.8 (I = 0.1 M, 37 degrees C). Kinetic evidence indicates the existence in the enzyme binding subsites S4, S3, S2, S3', S4', and S5' of a group(s) which become(s) negatively charged at higher pH. For most substrates, the magnitude as well as the pH dependence of kcat was unaffected by the presence of Lys or Arg in these peptides. In contrast, changes up to 5 orders of magnitude were observed for Km, depending on the number of basic residues and on their positions in the sequence. Km for a group of substrates at pH greater than 5.5 was lower than 50 nM. Values for kcat/Km for some substrates exceed the level of 10(8) M-1 s-1. Therefore, the free energy derived from ionic interactions in secondary binding sites influences mostly the binding step on the reaction pathway. This result is in contrast to the previous observations that the length and the hydrophobic character of the substrate residues in some positions influence kcat with little effect on Km toward shorter substrates of pepsin [Fruton, J. (1976) Adv. Enzymol. Relat. Areas Mol. Biol. 44, 1-36].
 ...
PMID:Secondary enzyme-substrate interactions: kinetic evidence for ionic interactions between substrate side chains and the pepsin active site. 313 29

A semi-empirical approach has been used to estimate the intramolecular electrostatic interactions in pepsin and penicillopepsin. The pH-dependence of the free energy electrostatic term was calculated, and the pH-dependence of the domain interactions has been estimated. As it was shown, the contribution of electrostatic interactions is rather small for the stabilization of the native structure. At the same time the electrostatic repulsion between domains increases with the increase of pH. The later can be the cause of the alkaline denaturation of pepsin and domain mobility.
Mol Biol (Mosk)
PMID:[Theoretical studies of the electrostatic interactions in aspartic proteinases, intramolecular interactions in pepsin and penicillopepsin]. 315 Aug 53


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