Catalase (CAT) is a critical antioxidant enzyme in largemouth bass (Micropterus salmoides) that converts toxic hydrogen peroxide (H2O2) into water and oxygen. It acts as a primary cellular defender, mitigating oxidative stress and preventing tissue damage during environmental challenges such as thermal shifts. Catalase is primarily localized in peroxisomes and mitochondria. It catalyzes the rapid decomposition of reactive oxygen species (ROS) into water and oxygen, maintaining cellular redox homeostasis. By clearing H2O2 efficiently, the enzyme protects lipid membranes, proteins, and DNA from oxidative degradation, thus maintaining cellular integrity. Largemouth bass frequently encounter aquaculture and environmental stressors like crowding, handling, transportation, and changing water temperatures. Catalase assists in managing these conditions.
The Catalase (NCBI accession number: XP_038560904.1) from Micropterus salmoides, comprising 527 amino acids, was retrieved from the UNIPROTKB database. In silico analysis of its physicochemical properties using ProtParam revealed an isoelectric point of 7.65, a molecular weight of 59919.52 Da, an instability index of 29.72, an aliphatic index of 62.90, and a GRAVY value of -0.583. Alanine is present in the highest number 38 (7.2%) and total number of negatively charged residues (Asp + Glu) were 59 in numbers. On the other hand, the total number of positively charged residues (Arg + Lys) was present to be 60 in numbers. Conserved domain (CD) analysis identified the catalase_clade_3 (cd08156) domain spanning amino acid residues 68 to 497, confirming its functional identity. Three-dimensional structural modeling of the protein was performed using AlphaFold2 available at https://neurosnap.ai/. Among the five predicted models, model 1 exhibited a mean local distance difference test (LDDT) score of 94.47, indicating very high structural accuracy. Further, this model was validated for its quality by Ramachandran plot which showed 97.6% residues in the most favored and additional allowed regions, ERRAT illustrated 88.7 score, which revealed a good structure quality of the model.
Furthermore, the NJ phylogenetic tree was generated using MEGAX analysis, which revealed that out of 21 homologous proteins, catalase in Siniperca chuatsi was observed as the closest evolutionary relative, supported by a weak bootstrap value.