Comparative Biochemistry and Physiology Part B 125 (2000) 211 – 217 Sulfurtransferases and the content of cysteine, glutathione and sulfane sulfur in tissues of the frog Rana temporaria M. Wro ´ bel a, *, P. Sura b , Z. Srebro b a Institute of Medical Biochemistry, Jagiellonian Uniersity, Collegium Medicum, 7 Kopernika St., 31 -034 Krako ´w, Poland b Institute of Biology, Jagiellonian Uniersity, Collegium Medicum, 31 -034 Krako ´w, Poland Received 11 February 1999; received in revised form 10 October 1999; accepted 4 November 1999 Abstract L-cysteine desulfuration was examined in tissues of Rana temporaria, in October and January. The activities of 3-mercaptopyruvate sulfurtransferase (MPST), cystathionine -lyase (CST) and rhodanese were primarily concentrated in frog liver and kidney. The values of CST and rhodanese activity, as well as sulfane sulfur compounds levels fell in the range characteristic of rat. For each of the investigated tissues changes noted in the enzymatic activities and in the level of glutathione (GSH), protein-bound cysteine (PbCys) and sulfane sulfur compounds were dependent on the month in which the determination was performed, and on the character of the tissue. In such tissues as the liver or gonads, high GSH levels and high activities of MPST (in the liver) or MPST and rhodanese (in the gonads) seemed to accompany protein biosynthesis during hibernation. PbCys, the level of which was consequently diminished in all tissues in January, compensated the absence of exogenous cysteine. A significantly reduced GSH level in the brain in January seemed to be correlated with decreased requirements of the tissue for this important natural antioxidant at diminished thyroid hormones levels in the serum and minimal oxygen consumption during the hibernation. In the kidney, the possible participation of sulfane sulfur compounds in detoxification processes requires elucidation, similarly as in protection against cellular oxidative stress at extremely low levels of GSH. © 2000 Elsevier Science Inc. All rights reserved. Keywords: 3-Mercaptopyruvate sulfurtransferase; Rhodanese; Cystathionase; Cysteine; Glutathione; Sulfane sulfur; Frog www.elsevier.com/locate/cbpb 1. Introduction 3-Mercaptopyruvate sulfurtransferase (EC 2.8.1.2), cystathionine -lyase (EC 4.4.1.1) and rhodanese (thiosulfate sulfurtransferase, EC 2.8.1.1) participate in L-cysteine desulfuration (Westley, 1980) (Scheme 1). The desulfuration pathway of L-cysteine metabolism may be impor- tant as a source of metabolically active reduced sulfur, i.e. divalent sulfur bonded only to other sulfur atoms (sulfane sulfur) (Westley, 1980; Sti- panuk, 1986; Ogasawara et al., 1994). Most sul- fane sulfur is capable of forming complexes with proteins and may be retained in this form for long periods in vivo prior to its oxidation to sulfate (Stipanuk, 1986). MPST and CST are known to be involved in forming sulfane sulfur, while rho- danese - in utilizing sulfur from the sulfane sulfur pool (Westley, 1980). Through the transaminative pathway L-cysteine is converted to 3-mercaptopy- ruvate (Cooper, 1986). MPST catalyzes the trans- fer of a sulfur atom from 3-mercaptopyruvate to one of several acceptors including cyanide, thiols, sulfite, and sulfinates (So ¨ rbo, 1957) or partici- * Corresponding author. Tel.: +48-12-4227400; fax: +48- 12-4223272. E-mail address: mbwrobel@cyf-kr.edu.pl (M. Wro ´ bel) 0305-0491/00/$ - see front matter © 2000 Elsevier Science Inc. All rights reserved. PII:S0305-0491(99)00171-6