Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Carboxy peptidase structure

Metals are used not only as labels in histochemistry and immunochemistry, but also for studying protein structure and properties. Some metal ions can serve as valuable probes by replacing the original ions in different metaloenzymes or other metaloproteins. For instance, cobalt can replace zinc on the active side of carboxy-peptidase, aldolase, carbonic anhydrase, phosphatase or yeast alcohol dehydrogena. ... [Pg.197]

The specificities of the various digestive exo- and endopep-tidases suggest that they act synergistically to fulfill a major nutritional function. The concerted action of trypsin, chy-motrypsin, pepsin, and carboxypeptidases A and B facilitate and ensure formation of essential amino acids. The chemical characteristics and metalloenzyme nature of two bovine exopeptidases, lens aminopeptidase and pancreatic carboxy-peptidase A, indicate similarities in their mechanisms of action. However, the aminopeptidase exhibits an unusual type of metal ion activation not observed unth carboxy-peptidase. Chemical and physicochemical studies reveal that the latter enzyme has different structural conformations in its crystal and solution states. Moreover, various kinetic data indicate that its mode of action toward ester substrates differs from that toward peptide substrates. The active site metal atom of carboxypeptidase figures prominently in these differences. [Pg.220]

The action of these two pancreatic exopeptidases on synthetic substrates, proteins, and peptides has been reviewed in detail by Neurath (1960). The specificity requirements which were deduced from studies with synthetic peptides have been confirmed by studies with polypeptides. The structural requirements of specific substrates for both types of carboxy-peptidase are analogous except for the nature of the amino acids which contain the free, ionized a-carboxyl group at the terminus of the substrate. Carboxypeptidase B hydrolyzes most rapidly those bonds formed by terminal lysyl and arginyl residues, whereas carboxypeptidase A hydrolyzes terminal bonds formed by a variety of aromatic, neutral, or acidic amino acids. Of the natural amino acids only carboxyl-terminal prolyl residues are resistant to the action of the enzyme. The rate of hydrolysis depends upon the nature of the side chains of the amino acids which form the susceptible bonds. Thus, differences in the rate of hydrolysis of different substrates may vary several thousandfold. The methods for application of these peptidases to hydrolysis of proteins have been discussed in detail by Canfield and Anfinsen (1963). [Pg.87]

Figure 2. Geometry of the [Zn(NH3)20H] model for the active site of carboxy-peptidase based on the crystal structure of the native enzyme (82). The interaction geometry with a water molecule corresponds to the coordinates from (82). Figure 2. Geometry of the [Zn(NH3)20H] model for the active site of carboxy-peptidase based on the crystal structure of the native enzyme (82). The interaction geometry with a water molecule corresponds to the coordinates from (82).
Much but not all of this work has dealt with proteins the three-dimensional structures of which have been determined by x ray lysozyme, ribonuclease, myoglobin, hemoglobin, cytochrome C, carboxy-peptidase, chymotrypsin, concanavalin, trypsin, elastase, and sub-tilisin. The principal nucleus has been the proton, but more recently 13 C has been studied by several groups. Other nuclei, such as 19 F, 31P, and 35Cl, have found limited application in special studies. [Pg.249]

In this superfamily, esterases, oxidoreductases, dehalogenases and carboxy-peptidases can also be found [73 and references therein]. Characteristically, these enzymes consist of a highly conserved /J-sheet region, surrounded by a-helical domains. A variable so called cap region completes their structural appearance. The active site of Hevea oxynitrilase has been found to He deep inside the protein molecule and is accessible via a narrow tunnel [73] (Fig. 4). [Pg.202]

Yet another example of the catalytic triad has been found in carboxy-peptidase II from wheat. The structure of this enzyme is not significantly similar to either chymotrypsin or subtilisin (Figure 9.15). This protein is a member of an intriguing family of homologous proteins that includes esterases such as acetylcholine esterase and certain lipases. These enzymes all make use of histidine-activated nucleophiles, but the nucleophiles may be cysteine rather than serine. Finally, other proteases have been discovered that contain an active-site serine or threonine residue that is activated not by a histidine-aspartate pair but by a primary amino group from the side chain of lysine or by the N-terminal amino group of the polypeptide chain. [Pg.234]

Dmitrenok, A., Iwashita, T, Nakajima, T., Sakamoto, B., Namikoshi, M., and Nagai, H. (2006) New cyclic depsipeptides from the green alga Bryopsis species application of a carboxy-peptidase hydrolysis reaction to the structure determination. Tetrahedron, 62, 1301-1308. [Pg.306]

Fig. 3.15. Variations and character of accessible surface area as a result of formation of secondary structures in six proteins pancreatic trypsin inhibitor (PTI), calcium binding protein (CBP), Bence-Jones protein REI (VIM), elastase (ELA), thermolysin (TLS), and carboxy-peptidase A (CPA). (A) Surface which remains accessible (B) surface which becomes buried. The partition, polar, charged, and nonpolar surface is indicated in all cases (according to Chothia, 1976). Fig. 3.15. Variations and character of accessible surface area as a result of formation of secondary structures in six proteins pancreatic trypsin inhibitor (PTI), calcium binding protein (CBP), Bence-Jones protein REI (VIM), elastase (ELA), thermolysin (TLS), and carboxy-peptidase A (CPA). (A) Surface which remains accessible (B) surface which becomes buried. The partition, polar, charged, and nonpolar surface is indicated in all cases (according to Chothia, 1976).
Asn-Pro, Asp-Met, Asp-Leu, Ala-Val, and Gly-Val were isolated from fermented sardine sauce further, the ACE-inhibitory peptides Ala-Pro, Arg-Pro, Gly-Pro, and Ala-Gly-Pro were isolated from fermented bonito sauce. Val-Pro was also identified in salted and fermented anchovy by Lee (1996). Among the peptides identified by Ichimura et al. (2003), Ala-Pro, Lys-Pro, and Arg-Pro showed strong and similar inhibitory activity. Ichimura et al. (2003) also isolated nine types of peptides containing Pro residues in their carboxy terminals. Due to the unique structure of Pro as an imino acid, peptide bonds containing Pro residues are often resistant to hydrolysis by common peptidases. This may be the reason why these Pro-containing dipeptides survived after long-term fermentation. Among these peptides, Lys-Pro was further evaluated in vivo in male SHRs (Charles River Japan, Yokohama) by oral administration. As shown in Fig. 5.3, orally administered Lys-Pro shows a tendency to lower the blood pressure of SHRs. [Pg.89]


See other pages where Carboxy peptidase structure is mentioned: [Pg.313]    [Pg.324]    [Pg.198]    [Pg.1005]    [Pg.95]    [Pg.1178]    [Pg.131]    [Pg.75]    [Pg.424]    [Pg.9]    [Pg.75]    [Pg.6]    [Pg.77]    [Pg.15]    [Pg.11]    [Pg.153]    [Pg.288]   
See also in sourсe #XX -- [ Pg.250 ]




SEARCH



Carboxy peptidases

Peptidases

© 2024 chempedia.info