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Studies on the status of lysine residues in phospholipase A2 from Naja naja atra (Taiwan cobra) snake venom.

ABSTRACT: Phospholipase A2 (PLA2) from Naja naja atra (Taiwan cobra) snake venom was subjected to lysine modification with trinitrobenzene sulphonic acid (TNBS), and two major trinitrophenylated (TNP) derivatives, TNP-1 and TNP-2, were separated by h.p.l.c. TNP-1 contained only one TNP group on Lys-6 and showed a marked decrease in enzymic activity, but still retained 45% of the lethal toxicity. Both Lys-6 and Lys-65 were modified in TNP-2, and modification of Lys-65 caused a further reduction of the lethal toxicity to 12.6%. However, the antigenicity of both TNP-1 and TNP-2 remained unchanged. The reactivity of Lys-6 and Lys-65 toward TNBS was greatly enhanced by Ca2+ and dihexanoyl-lecithin, suggesting that the two Lys residues are not directly involved in the binding of Ca2+ and substrate. The modified derivatives retained their affinity for Ca2+, indicating that Lys-6 and Lys-65 did not participate in the Ca2+ binding. The TNP derivatives could be regenerated with hydrazine hydrochloride. The biological activities of the regenerated PLA2 are almost the same as those of native PLA2. These results indicate that Lys-6 and Lys-65 are important for the biological activities of PLA2, and incorporation of a bulky TNP group on Lys-6 and Lys-65 might give rise to a distortion of the active conformation of PLA2.

SUBMITTER: Yang CC

PROVIDER: S-EPMC1133352 | biostudies-other | 1989 Sep

REPOSITORIES: biostudies-other

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Project description:ObjectiveThis study aimed to evaluate the clinical therapeutic efficacy of anti-snake venom serum blockade in treating local tissue necrosis caused by Chinese cobra (Naja atra) bites.MethodsPatients bitten by a Chinese cobra (Naja atra) (n = 50) that met the inclusion criteria were randomly divided into two groups: the experimental group (n = 25) and the control group (n = 25). The experimental group received regular as well as anti-snake venom serum blocking treatment, whereas regular treatment plus chymotrypsin blocking therapy was given to the control group. The necrotic volumes around snake wounds in these groups were detected on the first, third and seventh days. On the third day of treatment, some local tissues in the wounds were randomly selected for pathological biopsy, and the necrosis volume of the local tissue was observed. Furthermore, the amount of time required for wound healing was recorded.ResultsOn the third and seventh days post-treatment, the necrotic volume of the wound of the experimental group was much smaller than that of the control group, and the experimental group's wound healing time was shorter than that of the control group (all p < 0.05). Moreover, the pathological biopsies taken from the control group showed nuclear pyknosis, fragmentation, sparse nuclear density, and blurred edges, and the degree of necrosis was much higher than that of the experimental group.ConclusionsAnti-snake venom blocking therapy is a new and improved therapy with good clinical effect on local tissue necrosis caused by Chinese cobra bites; moreover, it is superior to conventional chymotrypsin blocking therapy in the treatment of cobra bites. It can better neutralize and prevent the spread of the toxin, reduce tissue necrosis, and shorten the course of the disease by promoting healing of the wound. Furthermore, this treatment plan is also applicable to wound necrosis caused by other snake toxins, such as tissue necrosis caused by elapidae and viper families.Clinical trial registrationThis trial is registered in the Chinese Clinical Trial Registry, a primary registry of International Clinical Trial Registry Platform, World Health Organization (Registration No. ChiCTR2200059070; trial URL:http://www.chictr.org.cn/edit.aspx?pid=134353&htm=4).

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Studies on the status of lysine residues in phospholipase A2 from Naja naja atra (Taiwan cobra) snake venom.

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