215F07-notes-12-5-07 - Chem 215 F07 Notes — Dr Masato...

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

View Full Document Right Arrow Icon
Image of page 1

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

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

Unformatted text preview: Chem 215 F07 Notes — Dr. Masato Koreeda — Page 1 of 2. Date: December 5, 2007 (7) Peptides (Chapter 23.8, pp 1007—1016) Enzyme: Any of a large class of complex ° primary structure: the order of AAs proteinaceous substances that are produced 0 secondary str: conformation of the peptide by living cells, that are essential to life by - tertiary str: stereo str created by bending acting like catalysts in promoting at the and folding of peptide chains cell temperature, reversible reaction (such 0 quaternary str: stereo str of the complex as hydrolysis and oxidation) Without made of several peptides themselves undergoing marked destruction 153 A in the process, but frequently requiring the single bonds; /' presence of activators (as metal ion) or Stifffiinbonds 110° \ «(,H coenz mes. 0 ( ====:—_—:::::::=======_—_=====::=:==== \fm A \C/C\H Chymotrypsin: a 241—amino acid endoprotease \21“ l 1‘32 6‘ Which shows specificity for cleavage after H c /.\N/,\H mix??? aromatic amino acids (Phe, Try, or Trp). H’ \ W i ::::::::’°““d shaded area represents the plane containing the peptide linkage and the two adjacent carbon atoms :45 ‘1; ”1. A representation of the chymotrypsin molecule showing the placement of histidine, aspartic acid, and serine at the active site. The hydrophobic pocket that binds the peptide residue during cleavage is below and to the right of the serine at position 195. Figure adapted from "A Family of Protein- Cutting Proteins." by Robert M. Stroud. Copyright © 1974 by Scientific American. Inc. All rights reserved. 0— active site é): disulfide bridge Active site Binding site Chem 215 F07 Notes — Dr. Masato Koreeda — Page 2 of 2. Date: December 5, 2007 R O _ - specmc for L-ammo acrds (or D» In a few cases) Peptide—NH k“ NfiLJL NH-peptide ~ usually specific for amino acid preceding cleavage site. 0 R‘ <chymotrypsin Trypsin - cuts after Phe, Tyr, Trp — cuts after Arg, Lys (aromatic sidechains) (basic sidechains) H O H O x/ N N / 3/ N / O H 0 fl Halli O 0 Specificity of endopeptidases. VISUALIZING THE may“ Acylation of the Active Site of Chymotrypsin substrate, protein or peptide Asp- 1 02 Ser- 1 95 \ hydrophobic pocket binding site tetrahedral intermediate acylated serine residue 0iThe use of the HO group as a nucleophile (as its anion) in this reaction is remarkable; the pKa of HOCHZR is about 16 and the pKa of the conjugate acid of histidine base is around 6— 8. This process is made thermodynamically favorable participation of Asp—102 in stabilizing the imidazolium cation of His—57. - The activity of enzymes is a powerful demonstration of the effect that lowering the energy of the transition state can have on the overall rate of the reaction. ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern