Trypsin contains a/an [aspartate/serine/histidine] in its specificity pocket to attract lysine and arginine side chains. It contains a potent nucleophilic [histidine/serine/aspartate] in its active site that is capable of attacking the electrophilic [carbon/nitrogen/oxygen] of the closest peptide bond. The [acyl-enzyme/specificity pocket/oxyanion] transition state is stabilized by the backbone amide hydrogens of glycine and serine. In this way, the enzyme is able to catalyze the [hydrolysis/ligation/metalysis/hydrogenation] of the peptide bond.

Identify and describe how you would PEGylate this peptide at its N- terminal amine. Discuss the reaction conditions you need to carry out the reaction and explain how pH affect selectivity of reaction. Draw the chemical structure of the resulting mPEG peptide conjugate.

I don't understand it. Can u help me? Can u help me to explain this to me, please

Many enzymes are switched "on" by attachment of a phosphate group at a specific serine somewhere on the protein (phosphorylation). The basic reaction is: E + ATP2 Ep + ADP Po SERINE PHOSPHO SERINC (Note the "squiggles" before the backone amide and carbonyl indicate the polypeptide chain continues on either side of the serine). For phosphorylation to have this effect, there has to be some equilibrium between inactive and active forms conformations of the enzyme: [Eactive] [Einactive] Einactive 2 Eactive; K* The same basic equilibrium must exist for the phosphorylated protein: [Ep,active] [Ep,inactive] EP,inactive 2 Ep,active; Kp = (a) If phosphorylation increases the measured activity of the enzyme, is K* or K larger? Why? (b) Does the phosphorylation site need to be near the site where the enzyme binds its substrate (e.g. the reactant whose chemistry it catalyzes)? Why or why not?

A protein has been sequenced after cleavage of disulfide bonds. The protein is known to contain 3 Cys residues, located as shown here. Only one of the Cys has a free —SH group, and the other two are involved in an —S—S— bond. The only methionine and the only aromatic amino acid (Phe) in this protein are in the positions indicated. Cleavage of the intact protein (i.e., withdisulfide bonds intact) by either cyanogen bromide or chymotrypsin does not break the protein into two peptides. Where is the —S—S— bond (i.e., AB, BC, or AC)?

A) Can you please tell me which of these A.A have a negative side chain? Names of choices in picture provided. B) Can you please tell me which A.A have a hydrophobic side chain and why?  Names and choices in picture provided. Thank You so much!!

the structures of chymotrypsin and other serine proteases revealed that the active sites of these enzymes shared a particular sterochemical arrangement of residues crucial to their activity. This came to be known as the catalytic triad, as it consisted of the oponyomous serine (Ser) residue, along with a histidine (His) and an aspartate (Asp) residue. Which of the following would result in the greatest decrease in function of the catalytic triad found in serine proteases? O Mutation to Ser, Cys, Asp O Mutation to Ser, His, Asp O Mutation to Cys, His, Asp O Mutation to Ser, His, Glu

What is the first thing that must occur in order for the catalysis of the peptide bond to begin. What is a specificity pocket? What are the preferences of chymotrypsin due to its specificity pocket?

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You are studying how your Lys-Val-Thr tripep de interacts with another pep de, which places an Asp in close proximity to the Lys on your pep de. How would the presence of an Asp side chain affect the pKa of the Lys side chain? Briefly explain your reasoning. (remember pKas are rela ve, pKa=log([H+][A-]/[HA])