How does the S1 pocket of trypsin differ from chymotrypsin?
The S1 binding pocket in trypsin and chymotrypsin are almost identical in primary sequences and backbone tertiary structures (Fig. 1). An important difference is that residue 189 is a negatively charged Asp in trypsin and a polar Ser in chymotrypsin.
Where is the specificity pocket?
The substrate residue N-‐terminal to the cleavage site (P1) largely determines the specificity of serine proteases. P1 binds S1, which is called the specificity pocket; its interactions were found early on to be a major determinant of the substrate specificity for trypsin, chymotrypsin and elastase.
What does aspartic acid do in chymotrypsin?
In trypsin, an aspartate residue (Asp 189) is present at the bottom of the S1 pocket in place of a serine residue in chymotrypsin. The aspartate residue attracts and stabilizes a positively charged arginine or lysine residue in the substrate.
What is subtilisin used for?
Subtilisins are proteolytic enzymes, mainly (>90 %) used in detergents and household cleaning products to remove proteinaceous deposits and stains. Subtilisins are of bacterial origin, and are produced by a fermentation process.
What does the s1 pocket do?
The S1 pocket is a deep hydrophobic pocket that allows long, uncharged amino acids like phenylalanine and tryptophan to fit in chymotrypsin. Binding in the S1 pocket positions the adjacent peptide bond at the active site for cleavage.
Why does trypsin cleave after lysine?
Trypsin cleaves the peptide bond between the carboxyl group of arginine or the carboxyl group of lysine and the amino group of the adjacent amino acid. The rate of cleavage occurs more slowly when the lysine and arginine residues are adjacent to acidic amino acids in the sequence or cystine.
Is subtilisin poisonous?
The results showed that oral consumption of subtilisin QK is of low toxicological concern. No adverse effects were observed at doses of 2500, 7500, and 25,000 FU/kg in the 28-day subchronic toxicity, and the no-observed-adverse-effect level (NOAEL) of subtilisin QK was 25,000 FU/kg.
What does trypsin cleave?