Portal de Periódicos da CAPES

Oxaloacetate decarboxylase from Klebsiella pneumoniae : size and shape of the enzyme, and localization of its prosthetic biotin group by electron microscopic affinity labeling

1988; Oxford University Press; Volume: 55; Issue: 1 Linguagem: Inglês

10.1111/j.1574-6968.1988.tb02794.x

1574-6968

Patricia Däkena, Manfred Rohde, Peter Dimroth, Frank Mayer,

Electrochemical sensors and biosensors

Oxaloacetate decarboxylase from Klebsiella pneumoniae is a membrane bound sodium-pumping biotin enzyme. In electron microscopic samples, the enzyme particle appeared rod-like, with a length of about 12.9 nm and a width of about 7.4 nm, and with two submasses. Based on electron microscopic comparison of full-size enzyme molecules and free α-subunits, it is concluded that oxaloacetate decarboxylase contains only one α-subunit per enzyme particle. The α-subunit of the enzyme revealed a subdivision into two domains of different sizes forming a ‘cleft’. Electron microscopic affinity labeling with avidin demonstrated that the biotin prosthetic group present on the α-subunit is located in this cleft, close to the complex formed by the β- and γ-subunits. The fact that ‘pairs’ but no higher specific aggregates could be observed after incubation with avidin, also indicates that only one copy of the α-subunit is present in an oxaloacetate decarboxylase particle.