Unraveling the mechanism of peptidases participation in the protein digestion of the whiteleg shrimp (Litopenaeus vannamei)

Abstract

This study aims to identify and analyze the temporal variation in the activity and relative abundance of peptidases in the midgut gland of the Pacific whiteleg shrimp, Litopenaeus vannamei, during digestion. The dynamic profiles of active peptidases throughout digestion were determined by zymogram profile analysis in the midgut gland of shrimp at different feeding times: preprandial, 1 h, and 3 h postprandial. Further proteomic analysis of midgut gland extracts confirmed the identity of different-class peptidases, as well as additional isoforms not previously reported, and changes in their relative abundance. Trypsins and chymotrypsins were the predominantly active peptidases throughout the digestion process. Cathepsin D was active during the preprandial time and 3 h after ingestion, whereas a metallopeptidase showed activity at preprandial time and 1 h postprandial. Additional trypsin isoforms of varying abundances were confirmed, while chymotrypsins and cathepsin L increased significantly, peaking 3 h postprandial. The results indicate significant changes in the relative abundance of new isoforms of trypsins, cathepsins, and metallopeptidases, as well as in the previously identified peptidases involved in shrimp food protein digestion over time.

Significance

The manuscript findings revealed the peptidases' potential participation in the digestive process of the Pacific whiteleg shrimp. The integrated results from different methods confirmed the identity and active state of some of the multiple peptidase classes in the shrimp midgut gland.

Additional trypsin, cathepsin, and metallopeptidase isoforms and their abundance changes were detected before and after ingestion. These results provide additional information about the complexity and efficiency of the protein hydrolysis mechanism of L. vannamei.