title: [Purification and properties of two enzymes of meta-cleaving the aromatic ring controlled by the biphenyl biodegradation plasmid pBS 241 from Pseudomonas putida].
abstract: It was shown that two metapyrocatechases (EC 1.13.11.2) function in Pseudomonas putida BS893. Biphenyl degradative plasmid pBS241 carries the genes of these enzymes. The basic properties of the both enzymes, i. e., MPC1 and MPC2, were investigated. It was found that MPC1 is an enzyme with a molecular mass of 135 kD and has a heterotetrameric subunit structure (alpha 2 beta 2), being made up of two non-identical polypeptides with Mr of 34 and 22.5 kD; pI is 5.15, the pH optimum is at 8.0, a temperature optimum is at 54 degrees C. MPC2 has a molecular mass of 154 kD and possesses a homotetrameric subunit structure (alpha 4); it consists of identical polypeptides with Mr of 41 kD and has a pI of 4.95, a pH optimum at 7.5 and a temperature optimum at 60 degrees C. The substrate specificity of the enzymes was studied, and the Km and Vmax values for substituted catechols were determined. MPC1 shows a high affinity for 2.3-dihydroxybiphenyl and hydrolyzes 3-methylcatechol and catechol (but not 4-methylcatechol) at a low rate. MPC2 has a moderate affinity for catechol, 3- and 4-methylcatechols, but is incapable of cleaving 2.3-dihydroxybiphenyl. Both enzymes share in common some typical properties of metapyrocatechases. The different role of MPC1 and MPC2 in biphenyl catabolism is discussed.
authors.forename: S A
authors.initials: SA
authors.lastname: Selifonov
authors.forename: I I
authors.initials: II
authors.lastname: Starovoĭtov
authors.forename: G K
authors.initials: GK
authors.lastname: Skriabin
mesh_terms: D001673:Biodegradation, Environmental; D001713:Biphenyl Compounds / Q000493:pharmacokinetics*; D050557:Catechol 2,3-Dioxygenase; D055598:Chemical Phenomena; D002621:Chemistry; D049308:Dioxygenases; D007700:Kinetics; D008970:Molecular Weight; D010105:Oxygenases / Q000302:isolation & purification* / Q000378:metabolism; D010957:Plasmids; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics*
chemical_list: D001713:Biphenyl Compounds; D010105:Oxygenases; D049308:Dioxygenases; D050557:Catechol 2,3-Dioxygenase
vernacular_title: Ochistka i svoĭstva dvukh fermentov meta-rasshchepleniia aromaticheskogo kol'tsa, kontroliruemykh plazmidoĭ biodegradatsii bifenila pBS 241, iz bakterii Pseudomonas putida]