Molecular Characterization, Recombinant Expression, and Functional Analysis of Carboxypeptidase B in Litopenaeus vannamei

<b>Background/Objectives:</b> The Pacific white shrimp (<i>L. vannamei</i>) is economically significant, and its growth is regulated by multiple factors. Carboxypeptidase B (CPB) is related to protein digestion, but its gene sequence and features in <i>L. vannamei</i> are not fully understood. This study aimed to explore the molecular and functional properties of CPB in <i>L. vannamei</i>. <b>Methods:</b> The Lv-CPB gene was cloned, and bioinformatics analysis, qRT-PCR, in situ hybridization, recombinant protein expression in <i>Escherichia coli</i>, and an enzyme activity assay were performed. <b>Results:</b> The Lv-CPB gene is 1414 bp long with a 1263 bp ORF encoding a 420-amino-acid protein. It is stable, hydrophilic, and is highly expressed in the hepatopancreas. The recombinant protein was efficiently expressed with a molecular weight of about 47 kDa. The optimal pH and temperature for Lv-CPB were 8.0 and 50 °C, respectively. <b>Conclusions:</b> This study revealed the molecular and functional characteristics of Lv-CPB, providing insights into its role in shrimp digestion, as well as suggestions for improving aquaculture practices.