We study the CaM-peptide interactions for four CaM-related peptides with different calcium equivalents, using the hCaM-M124C-mBBr biosensor and Molecular Dynamics (MD). Due to the high sensitivity of the biosensor, we were able to calculate five Kds based on the number of calcium equivalents for each peptide, showing a directly proportional relationship between the degree of calcium saturation and the increased affinity for the Calspermin, nNOS, and skMLSK peptides; while the CaV1.1 peptide has a degree of affinity independent of the number of calcium equivalent. On the other hand, the MD studies were designed based on the experimental results; I) visualizing the effect of the gradual elimination of calcium in Holo-CaM and II) analyzing the CaM-Peptide complexes with and without calcium. We observe that the gradual addition of calcium increases the flexibility of Holo-CaM. Concerning CaM-Peptide complexes, it presents differences in both the ΔGT and the RMSD. These results demonstrate the importance of the use of biosensors and the power of MD to make inferences in systems such as CaM-peptide complexes.

Azo dyes have become a threat to public health because of its toxicity and carcinogenicity. Azoreductase enzyme plays a pivotal role in the degradation of azodyes released by industrial effluents and other resources. The degradation pathway has to be studied in detail for increasing the activity of azoreductase and for better degradation of azo dyes. But the data available on cyanobacterial azoreductase enzyme and its degradation pathway are still very less. Therefore the present work explored the azoreductase pathway of the cyanobacterium Nostoc sp. PCC7120 for better understanding of the degradation pathway and the other accessory interacting proteins involved. The accessory interacting proteins of azoreductase from cyanobacterium Nostoc sp. PCC7120 were obtained from STRING database. The proteins do not have a comprehensive three dimensional structure and are hypothetical. The secondary structure and functional analysis indicated that the proteins are all soluble proteins, without disulphide bonds and have alpha helices only. The structural prediction and docking study showed that alr2106, alr1063 and alr2326 have best docking result which tally with the STRING database confidence score and thus these proteins could possibly enhance the azoreductase activity and better dye degradation. These results will pave way for further increase in azoreductase activity and for better understanding of the dye degradation pathway.