STUDIES ON BAKERS' YEAST LACTATE 

 DEHYDROGENASE 



By T. HoRio,* J. Yamashita, T. Yamanaka, M. NozAKif 



AND K. OkUNUKI 



Department of Biology, Faculty of Science, University of Osaka, Osaka 



Yakushiji and Mori (1937) reported the extraction and partial purification 

 of a 'Z>-type cytochrome' from bakers' yeast. Using the preparation, 

 Okunuki and Yakushiji (1940) proposed a scheme for the terminal electron- 

 transferring system as follows: 



Substrate -^ Coenzyme ->■ 'Cytochrome f -^ Cytochrome c -- Oxygen 



t t t 



Dehydrogenase Diaphorase Cytochrome oxidase system 



Borei (1945) reported that 'cytochrome f was not extracted according to the 

 method of Yakushiji and Mori. On re-examination, the method, with shght 

 modifications, was found suitable for the extraction of cytochrome c and 

 cytochrome Z)2, but not for the extraction of a typical cytochrome b. After 

 the extraction of both cytochromes, the cytochrome b still remained in the 

 cellular particles. The description by Yakushiji and Mori is therefore 

 regarded by us as the first detection and partial purification of cytochrome ^3- 

 Both cytochromes c and b^ extracted from bakers' yeast have been crystallized 

 (Hagihara, Horio, Yamashita, Nozaki and Okunuki, 1956; Yamashita, 

 Higashi, Yamanaka, Nozaki, Mizushima, Matsubara, Horio and Okunuki, 

 1957). 



Appleby and Morton (1954, 1959a, b) succeeded in crystallizing lactate 

 dehydrogenase (Y-LDH) from bakers' yeast. Their crystalline Y-LDH 

 (molecular weight, 80,000) contained riboflavin phosphate, deoxyribo- 

 polynucleotide (Morton, 1955, 1958; Appleby, 1957) and haem iron, but 

 no non-haem iron. Moreover, the enzyme was capable of reducing cyto- 

 chrome c and methylene blue at the expense of lactate in the absence of any 

 coenzyme and showed absorption spectra just like a Zj-type cytochrome. In 

 its lactate-reduced form the absorption peaks of the preparation were at 

 556 mfi (a-band), 527 m/i (/:/-band) and 423 m/i (y-band), and in its oxidized 



* Present address: Graduate Department of Biochemistry, Brandeis University, 

 Waltham 54, Mass., U.S.A. 



t Present address: Department of Agriculture, University of California, Berkeley 4, 

 California, U.S.A. 



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