Structure of wheat serine carboxypeptidase II at 3.5-A resolution. A new class of serine proteinase.
The structure of serine carboxypeptidase II from wheat bran has been determined to 3.5-A resolution by multiple isomorphous replacement, solvent flattening, and crystallographic refinement. The amino acid sequence has been fit to the electron density map and the model refined to a conventional crystallographic R factor of 20.9%. The molecule is an alpha + beta protein and contains a "catalytic triad" (Asp338, His397, and Ser146) similar in arrangement to those in chymotrypsin and subtilisin. The -fold of the polypeptide backbone is, however, completely different from those enzymes. This suggests that this is a third example of convergent evolution to a common enzymatic mechanism. The -fold is, on the other hand, surprisingly similar to that of the zinc proteinase carboxypeptidase A.
Liao
D I
DI
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Remington
S J
SJ
D000595:Amino Acid Sequence; D001665:Binding Sites; D002268:Carboxypeptidases; D008958:Models, Molecular; D011487:Protein Conformation; D014908:Triticum / Q000201:enzymology*; D014961:X-Ray Diffraction
D002268:Carboxypeptidases; C022633:serine carboxypeptidase