Abstract
Some physicochemical properties of the purified LM protein isolated from submandibular saliva of IPR-treated rats were studied. The molecular weight of the LM protein was estimated to be 12000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its isoelectric point was 4.75. The sugar content of the protein was estimated to be 1.62% and the calcium content was 1.07 mol/mol of the protein. Phosphorus and magnesium were not detectable. Amino acid analysis revealed that the protein cotained relatively large amounts of aspartic acid (asparagine) (14.8%), glutamic acid (glutamine) (14.8%) and serine (11.6%), and small amounts of proline (1.9%) and glycine (5.4%). A part of the amino acid sequence from the N-terminal was determined ; the N-terminal was proline, followed by five hydrophobic amino acids. These results clearly indicate that the LM protein isolated from submandibular glands of IPR-treated rats is different from prolinerich proteins previously isolated by others from parotid glands of IPR-treated rats.
