Isolation and Amino Acid Sequence of SAP-1, an Acidic Protein of Human Whole Saliva, and Sequence Homology with Human γ-Trace

Abstract

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 $II1$ PGGIYDADLNDEWVQRA $L20$ HFAISEYNKATEDEYYRRP $L40$ QVLRAREQTFGGVNYFFDV $E60$ VGRTICTKSQPNLDTCAFH $E80$ QPELQKKQLCSFEIYEVPW $E100$ DRMSLVDSRCQE $A113$ . 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 γ-trace, a basic microprotein present in cerebrospinal fluid and in urine of patients with renal failure.