Ascorbic acid sulfate sulfohydrolase (C2 sulfatase): the modulator of cellular levels of L-ascorbic acid in rainbow trout.

Abstract

The enzyme L-ascorbic acid 2-sulfate sulfohydrolase (C2 sulfatase) was purified from rainbow trout liver. The enzyme catalyzes the hydrolysis of L-ascorbic acid 2-sulfate and has a pH optimum at 6.0. It has a molecular weight of about 117,500 at pH 5.0 and is inhibited by a number of sulfhydryl blocking agents including L-ascorbic acid. C2 sulfatase activity was observed in most metabolic organs of rainbow trout. These findings suggest that the physiologic role of the enzyme is to maintain adequate cellular concentrations of L-ascorbic acid in the fish. The activity of the enzyme is controlled by L-ascorbic acid through feedback inhibition. Comparison of kinetic constants and inhibition patterns suggests that C2 sulfatase is structurally identical to human arylsulfatase A. However, unlike C2 sulfatase, human arylsulfatase A may not be involved in ascorbate metabolism. Its physiologic substrate is reported to be cerebroside-3-sulfate, not L-ascorbic acid 2-sulfate. A scheme is proposed to account for the functional divergence of these two structurally identical enzymes.L-Ascorbic acid (C1) plays a critical role in all living organisms. Trout, salmon, and a number of other fish species (1-6) have a dietary requirement for C1. As in mammalian systems, C1 appears to be involved in collagen synthesis. Fish reared on C1-deficient diets develop signs traceable to impaired collagen biosynthesis; i.e., lordosis, scoliosis, vertebral dislocation, deformation of support cartilage, and delayed wound repair (4-6).C1 is the most chemically unstable component of fish feeds. L-Ascorbic acid 2-sulfate (C2), a more stable derivative of C1 was discovered in brine shrimp cyst (Artemia salina) (7,8). It was also detected as a metabolite in human urine (9) and in the liver, spleen, adrenal glands, and bile of rats (10, 11). C2 promptly arrested signs of fish scurvy in rainbow trout reared on a scorbutic diet (12). In a group ofrainbow trout fed for 1 yr an artificial diet containing C2 as sole source of ascorbate, normal growth, diet efficiency, and absence of scurvy indicated that C2 sulfate was an adequate source of C1.Enzymatic hydrolysis of C2 to C1 by a sulfohydrolase would be a critical step in the utilization ofC2 as a vitamin source. This activity has been detected in fish tissues (12, 13), in the liver of the gastropod Charonia lampas (14), and in extracts of mammalian tissues (15,16). The ability ofrainbow trout to utilize C2 as sole dietary source ofC makes this fish a model test organism for the study of the sulfatase. This paper deals with the purification and properties of C2 sulfohydrolase (C2 sulfatase) from rainbow trout liver. Experimental evidence suggests that the enzyme modulates cellular levels of C1 in the fish.MATERIALS AND METHODS Materials. Ultrapure grade C1 was from Hoffmann-La Roche. The dipotassium salt of C2 was generously donated by Paul A. Seib (Kansas State University). Dipotassium 4-nitrocatechol sulfate, crystalline 4-nitrocatechol, crystallized and lyophilized bovine serum albumin, apofer...

Ascorbic acid mediates acetylcholine receptor increase induced by brain extract on myogenic cells.

“…D-Isoascorbic acid also mimics the biological activity of ascorbic acid on fibroblasts in vitro (34). The antiscorbutic effects of ascorbic acid 2-0-sulfate and dehydroascorbic acid have been attributed to the existence of cellular systems or enzymes capable of converting them to ascorbic acid (31)(32)(33)(35)(36)(37). Thus, the activity of these compounds in our assay system is consistent with ascorbic acid being a specific effector of AcChoR increases on L5 cells.…”

Influence of some environmental variables on the ascorbic acid status of mullet, Mugil cephalus L., tissues

“…It has been suggested that AsA 2-sulphate is a storage form of AsA in rainbow trout (Halver et al, 1975) and that the enzyme AsA 2-sulphate sulfohydrolase modulates the cellular levels of AsA by its action on AsA 2-sulphate (Benitez & Halver, 1982). In the present study seasonal changes were found in the AsA 2-sulphate content of mullet brain and hepatic tissues, but the pattern of fluctuations differed from that of AsA and no clear relationship between the tissue levels of these two parameters was evident.…”

L-Ascorbyl-2-Sulfate Alleviates Atlantic Salmon Scurvy

“…-ascorbyl-2-sulfate (C2S) is a heat-and oxidation-resistant compound which can be con-L verted into ascorbic acid by C2sulfatase in rainbow trout tissues (1). Efficacy of C2S as a vitamin C source for rainbow trout (Oncorhynchus mykiss) was reported in 1993 (2), but other reports questioned the efficacy of C2S (34).…”