lecture 14 - Serine 195 is present in all of the serine...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Serine 195 is present in all of the serine proteases. Hydroxyl of serine is responsible for attacking the amide bond that’s cleaved. In addition, enzyme has specificity pocket which comminades side chains where carboxyl sides will be cleaved. Chymotrypsin- deep specificity pocket. Tetrahedral intermediate generated first, when substrate is bound, prior to cleavage of peptide bond there is tetrahydral intermediate that has oxyanion, which is stabilized by serine proteonases. With aminonitrogens it is stabilized. There is another oxyanion---when acyl enzyme is hydrolyzed, liberated. Acylation step precedes oxyanion and deacylation is also involving oxyanion. Synthesize enzyme as zynogens. Which are almost identical to active enzymes, with slight difference in amino acids. Cleavage of peptide bond in zynogens permits the orientation for activating enzyme. Enteropeptidase and Trypsin cleave bond of trypsinogen in order to make activated trypsin. Intestinal lumen: Trypsin can activate chymotrypsin. Once you activate trypsinogen with enteropeptidase, all other enzymes will be active. Foreign materials. Digest bacteria, etc. proteases do this Neutrophils: defend body, uses serine proteases that are found in granules in cell. Leukocyte or neutrophil elastase, cathepsin G and proteonase 3. There is no zynogen step required, released upon neutrophil activation. In addition to serine proteonases that are packaged in granules, there are metalo proteanases: collagenitic enzyme which cleaves the collagen triple helices of collagen. The once that are not in coiled coil. The process can get out of hand if inflammation is too severe. Neutrophils release the enzymes, not only elastin and all other connective tissue proteins. It goes after all stuff… digestion of bacteria is ok but digestion of connective tissue-not good, avoid collateral damage. body deals with is by makes selective antiproteanases. Inhibitors, that are competitive, go for active side. Unlike competitive inhibitors that are reversible, these inhibitors make quiasi complex, shut enzymes down until there is some mechanism for clearing enzyme inhibitor complex. Key to regulation to enzymatic activity during inflimation is the avialibity of antiproteanases that are in plasma or serum so that when neutrophils releases proteonases these inhibit to avoid collateral damage. This is balancing act, antiproteonases will inhibit excess proteonases. Neutrophils have a way to avoid total shut down. All proteonases released by neutrophils, serine proteonases especially elastase go after the endogenous inhibitors of matrix metaloproteonases (tissue inhibitors, alpha 2 macroglobulin) . Elastase inhibits natural inhibitors of metaloproteonases. Meanwhile
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/30/2010 for the course BIO 351 taught by Professor Hoffmann,j during the Fall '08 term at SUNY Stony Brook.

Page1 / 4

lecture 14 - Serine 195 is present in all of the serine...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online