Isolation and Primary Characterization of an Amidase from Rhodococcus rhodochrous

E. K. Kotlova^*, G. G. Chestukhina, O. B. Astaurova, T. E. Leonova, A. S. Yanenko, and V. G. Debabov

Institute of Genetics and Selection of Industrial Microorganisms, 1-yi Dorozhnyi Proezd 1, Moscow, 113545 Russia; fax: (095) 315-0501; E-mail: lab11@vnigen.msk.su

^* To whom correspondence should be addressed.

Received November 11, 1998

---

Amidase (EC 3.5.1.4) was purified to homogeneity from Rhodococcus rhodochrous M8 using isopropanol fractionation and exchange chromatography on Mono Q. The isolated amidase consists of four identical subunits with molecular weight 42 ± 2 kD. The activity of the enzyme is maximal at 55-60°C and within the pH range 5-8. The amidase from R. rhodochrous M8 is highly sensitive to such sulfhydryl reagents as Hg²⁺ and Cu²⁺. Chelators (EDTA and o-phenanthroline) and serine proteinase inhibitors (PMSF and DIFP) did not inhibit the activity of the enzyme. The enzyme exhibits hydrolytic and acyl transferase activity and does not possess urease activity. Aliphatic amides (acetamide and propionamide) were the best substrates for the amidase from R. rhodochrous M8, whereas bulky aromatic amides were poor substrates of this enzyme. The properties of the isolated enzyme are similar to those found in the corresponding amidase from Arthrobacter sp. J-1 and an amidase with wide substrate specificity from Brevibacterium sp. R312.

---

KEY WORDS: Rhodococcus rhodochrous, amidase, purification, properties, substrate specificity

---