Twenty-four Suffolk x Hampshire ram lambs (average 46 kg) were assigned to one of three diets containing rapeseed meal (RM), soybean meal (SBM), or whole rapeseed-soybean meal (RSSBM) as the protein source. Diets contained 75% roughage, 14% CP and 2.0 Mcal of ME/kg and lambs were allowed ad libitum access to diets for 35 d. Lipid composition of the longissimus, semimembranosus, and triceps brachii muscles and their corresponding s.c. adipose tissue was determined by gas-liquid chromatography (GLC). The total lipid content in either muscle or subcutaneous fat was not different (P greater than .01) by diet. In lean tissue, palmitic and palmitoleic acids were higher and stearic acid was lower (P less than .01) in rams fed RM than in rams fed RSSBM or SBM, regardless of anatomical location. In the s.c. adipose tissue, the amounts of myristoleic, pentadecylic, and palmitoleic acids were lower and the amount of stearic acid was higher (P less than .01) in rams fed RSSM than in those fed RM or SBM, regardless of anatomical location. The semimembranosus and triceps brachii muscles from all treatments contained 12 to 19% more polyunsaturated fatty acids (PUFA) than the longissimus muscle. The cholesterol content of the three muscles was highest in SBM-fed lambs, lowest in RM-fed lambs, and intermediate in RSSBM-fed lambs. These results demonstrate that dietary treatments of the types used in the present study elicit changes in fatty acid composition of both adipose and muscle tissue without affecting the quantity of total lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

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545The glyoxalase-enzyme system, which has been known since 1913 [l, 21, is widely distributed in nature and catalyses the conversion of methylglyoxal (or other a-ketoaldehydes) to i)-lactate (or other a-hydroxy acids) with reduced glutathione serving as the cofactor [3-71. The system consists of two enzymes, glyoxalase I and glyoxalase I1 [8]. Glyoxalase I (EC 4.4.1.5) acts upon the equilibrium adduct of methylglyoxal and glutathione, a hemimercaptal, to form the thioester, S-i Aactoylglutathione (SLG). Glyoxalase I1 (EC 3.1.2.6) hydrolyses the thioester to regenerate glutathione and to liberate free iAactic acid. Many suggestions for the function(s) of the glyoxalase system have been made and include protection against a-ketoaldehyde toxicity [8], regulation of cell growth [9, 101 and a glycolytic bypass from dihydroxyacetone phosphate to I )-lactate, via methylglyoxal synthase and the glyoxalases [ 111. Several years ago the glyoxalase system was reported to affect cell-free microtubule assembly [ 121. Synthesis of competitive inhibitorsOne of the approaches employed in exploring possible functions of the glyoxalases has been with the use of competitive inhibitors of glyoxalase I and glyoxalase 11. From 1957 onwards, a number of glyoxalase I inhibitors, derived from Flutathione, have been synthesized [ 13-17]. More recently competitive inhibitors of glyoxalase 11, also derived from glutathione, have been prepared and studied [ 18-21 1 ; these inhibitors are typically thiocarbonate or thiocarbonate-carbamate derivatives of glutathione. Those derivatives which have been found to be effective glyoxalase I1 inhibitors are summarized in the generalized structure: OOCHCI lICHLCONHCHCONHCH,COO -I I NI I S I I K' R Abbreviations used: CH-G, S-carboxybenzoxylglutathione; DiFMOC-G, N,S-fluorenylmethoxycarbonylglutathione; FMOC-G, S-fluorenylmethoxycarbonylglutathione; 0-, m-, p-NCH-G, S-(0, m-, p-nitrocarbobenzoxyglutathione); SLG, S-1)-lactoylglutathione. This report is concerned mainly with the synthesis of new glyoxalase I1 inhibitors (in particular N,S-bisfluorenylmethoxycarbonylglutathione [DiFMOC-GI and some of its diesters) and their effects on purified mammalian glyoxalase I1 and on mammalian cells in culture. We will touch on the subject of the inhibition of purified preparations of glyoxalase I1 by a variety of purine nucleotides as well. W e have prepared S-fluorenylmethoxycarbonylglutathione (FMOC-G) and N,S-biscarbobenzoxy glutathione (DiCB-G) previously and have found them to be quite potent and specific competitive inhibitors of glyoxalase I1 purified from mammals and plants 1201. Recently we have prepared and studied N,S-bisfluorenylmethoxycarbonyl glutathione (DiFMOC-G). Table 1 lists a number of glyoxalase I1 inhibitors that have been reported, as well as the newly synthesized DiFMOC-G. The latter compound is the most potent competitive inhibitor of glyoxalase I1 known to us that has been synthesized ( K , = 0.75 pM, calfliver glyoxalase 11). The thiocarbonate derivatives of glutathione, which bind ve...