Cysteine proteases are remarkably similar to serine proteases (like chymotrypsin), except they have a cysteine in their active site rather than a serine. Using the mechanism that we discussed for serine proteases, draw a corresponding mechanism for a cysteine protease cleaving the bond between an alanine-glycine dipeptide. Note that cysteine proteases do not require an aspartate in their active site. Also note that the cysteine is usually in its thiolate form (deprotonated) and the histidine is in its imidazolium form (fully protonated) in the resting state of the enzyme.
Nucleotides
It is an organic molecule made up of three basic components- a nitrogenous base, phosphate,and pentose sugar. The nucleotides are important for metabolic reactions andthe formation of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
Nucleic Acids
Nucleic acids are essential biomolecules present in prokaryotic and eukaryotic cells and viruses. They carry the genetic information for the synthesis of proteins and cellular replication. The nucleic acids are of two types: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The structure of all proteins and ultimately every biomolecule and cellular component is a product of information encoded in the sequence of nucleic acids. Parts of a DNA molecule containing the information needed to synthesize a protein or an RNA are genes. Nucleic acids can store and transmit genetic information from one generation to the next, fundamental to any life form.
Cysteine proteases are enzymes that degrade proteins. You may have heard of some examples of these types of proteins before! Bromelain is an enzyme found in pineapple that is commonly used as a meat tenderizer and is the reason Jell-O with fresh pineapple will not solidify. Cysteine proteases are remarkably similar to serine proteases (like chymotrypsin), except they have a cysteine in their active site rather than a serine. Using the mechanism that we discussed for serine proteases, draw a corresponding mechanism for a cysteine protease cleaving the bond between an alanine-glycine dipeptide. Note that cysteine proteases do not require an aspartate in their active site. Also note that the cysteine is usually in its thiolate form (deprotonated) and the histidine is in its imidazolium form (fully protonated) in the resting state of the enzyme.
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