10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 3 2014 (July- September) Various studies suggest the involvement of nitrate reductase in gold nanoparticle synthesis from different bacterial sources. The present study focuses on the lessThan i greaterThan in silico lessThan /i greaterThan characterization of four subunits namely alpha, beta, gamma and delta of respiratory nitrate reductase enzyme using online tools and softwares in lessThan i greaterThan Pseudomonas denitrificans lessThan /i greaterThan .CodonW and CAIcal server are used to perform codon usage biasness study on the respiratory nitrate reductase genes of lessThan i greaterThan P. denitrificans. lessThan /i greaterThan Further different parameters of the physicochemical characterization were analysed by CLC Protein workbench, Expasy ProtParam, BLAST and COBALT. The analysis of various above parameters shows that the expression of gamma subunit is more out of all four subunits, hence suggesting the major involvement of it in gold nanoparticle synthesis. This may help in future to find out ways to enhance gold nanoparticle production in lessThan i greaterThan P. denitrificans lessThan /i greaterThan and other related organisms. RASHMI GUPTA, KOEL MUKHERJEE AND SNEHA SINGH Gold nanoparticles, Pseudomonas denitrificans, nitrate reductase, Codon usage biasness. 376-388