Isolation and amino acid sequence of SAP-1, an acidic protein of human whole saliva, and sequence homology with human gamma-trace.

A low-molecular-weight acidic protein was isolated from human whole saliva by DE32 column chromatography and designated as SAP-1. The amino acid sequence was determined by conventional methods to be (sequence in text). The protein consisted of 113 residues and the calculated molecular weight was 12,552. Computer analysis revealed the presence of 54% sequence homology between SAP-1 and gamma-trace, a basic microprotein present in cerebrospinal fluid and in urine of patients with renal failure.