Abstract
Caseins determine the physicochemical, physiological, and biological characteristics of milk. Four caseins-alpha-S-1, alpha-S-2, beta, and kappa-were analyzed phylogenetically and in silico and characterized regarding chemical, antimicrobial, and antioxidant features in five dairy animals: Arabian camels, sheep, goats, cattle, and water buffalos. The sequence of full-length amino acids of the four caseins for the five species was retracted from the NCBI GenBank database. Multiple sequence alignment is used to examine further the candidate sequences for phylogenetic analysis using Clustal X and NJ-Plot tools. The results revealed that sheep and goats possess strong similarities (98.06%) because of their common ancestor. The same was observed with cattle and water buffalos (96.25%). The Arabian camel was located in a single subclade due to low similarity in casein residues and compositions with other dairy animals. Protein modeling showed that alpha-S1- and alpha-S2-caseins possess the highest number of phosphoserine residues. The in silico computed chemical properties showed that beta-casein recorded highest hydrophobicity index and lowest basic amino acid content, while alpha-S2-casein showed the opposite. The computed biological parameters revealed that alpha-S2-casein presented the highest bactericidal stretches. Only Arabian camel beta-casein and k-casein showed one bactericidal stretches. The analysis also revealed that beta-casein, particularly in Arabian camels, possesses the highest antioxidant activity index. These results support the importance of the bioinformatics resources to determine milk casein micelles' chemical and biological activities.