Purification and characterization of betacyanoalanine synthase from <i>Pseudomonas straminea</i>

Abstract

Beta-cyanoalanine synthase (EC 4.4.1.9) is a cyanide detoxifying enzyme obtained from Pseudomonas straminea isolated from the effluents of Iron and Steel Smelting Company in Ile-Ife, Osun State. The effluent water samples were screened for their ability to detoxify cyanide and isolates obtained were then screened for b-cyanoalanine synthase production. The samples were screened for their ability to detoxify cyanide and isolates obtained were then screened for β-Cyanoalanine Synthase production. The enzyme was purified through Lyophilization, ion exchange chromatography on CM-Sephadex c-25 and Gel filtration on Biogel P-100. The enzyme had a specific activity of 273.75 U/mg with a purification fold of 2.41 and a yield of 28.90. The native molecular weight of the enzyme was estimated as 54.9 KDa and subunit molecular weight of 60.3 KDa. The K m values of the enzyme for sodium cyanide and L-Cysteine were 8.33 ± 0.05 mM and 1.25 ± 0.26 mM respectively while their maximum reaction velocities were 14.705 ± 0.32 MU/ml/min and 0.1 ± 2.48 MU/ml/min respectively. The optimum temperature and pH for activity were determined to be 40 o C and 9.0. The metals tested at the different concentrations of 1 mM, 5 mM and 10 mM enhanced the activity of the enzyme. Inhibition studies on β-Cyanoalanine Synthase Pseudomonas straminea showed that the activity of the enzyme was affected by mercuric chloride, glycine, EDTA and iodoacetamide. The study concluded that β-Cyanoalanine Synthase from Pseudomonas straminea may possess potential bioremediation properties for detoxification of cyanide polluted wastewaters.

Isolation and statistical optimization of rhodanese (a thiosulphate sulphur transferase) production potential of Klebsiella oxytoca JCM 1665 using response surface methodology

“…The decline in rhodanese production may be due to exhaustion of the nutrients or accumulation of other products or metabolites which are both inhibitory to the growth of the bacterium and rhodanese production. This result agrees with the findings of Okonji et al (2018) who observed a decrease in metabolite production after 15 hours of incubation. Linawati et al (2002) also reported the influence of environmental conditions on the production of pigment by Serratia marcescens.…”

“…The ability of P. putida and B. pumilus to make use of cyanide as carbon source was also reported by Kandasamy et al (2015). Okonji et al (2018) also reported the ability of Pseudomonas straminea to make use of peptone as nitrogen source. The high cyanide tolerance of K. oxytoca observed was probably due to its ability to synthesize rhodanese as a means of surviving in cyanide contaminated environment.…”

Structural and functional characterization of β-cyanoalanine synthase from Tetranychus urticae

“…a pyridoxal phosphate-dependent enzyme (Arenas-Alfonseca et al, 2018) that catalyzes the substitution of L-cysteine sulfhydryl moiety with cyanide, forming the non-protein amino acid, βcyanoalanine with the release of hydrogen sulfide (Figure 1A) (Okonji et al, 2018). Released H2S can block the mitochondrial respiratory pathway and can be further detoxified by O-acetyl-Lserine sulfhydrylase (OASS) (Alvarez et al, 2012).…”

“…The host plant range of TSSM includes a number of plants that synthesize cyanogenic glucosides. These compounds are not toxic on their own and require hydrolysis to generate a reactive hydroxynitrile that releases toxic HCN (Okonji et al, 2018). The hydrolysis occurs upon tissue disruption that can occur during herbivore feeding.…”