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석이로부터 분리한 페놀성 화합물의 phospholipase A_2 저해활성
김진우,송경식,유익동,장현욱,유승현,배강규,민태진 충남대학교 생물공학연구소 1997 생물공학연구지 Vol.5 No.-
호알카리성 진균 Cephalosporium sp. RYM-202가 생산하는 alkaline xylanase (CX-III)의 작용에 의해 xylan 기질로부터 생성되는 주요 가수분해 산물은 xylobiose와 중합도가 4 이상인 xylooligosaccharides이었다. 이 효소는 xylobiose에 대한 분해능을 가지고 있지 않지만 xylotriose로부터는 xylobiose를, xylotetraose로부터는 xylobiose와 xylotriose를 주산물로 형성하였다. 이러한 결과들은 CX-III가 transglycosidase 활성을 소유하는 전형적인 endo-type xylanase임을 보여준다. N-bromosuccinimide에 의한 CX-III의 화학적 변화 실험 결과 효소 1분자 당 2개의 tryptophan 잔기가 활성에 관여하는 것으로 나타났다. 그러나 iodoacetamide 및 diethylpyrocarbonate에 의한 효소활성의 저해효과는 나타나지 않음으로써 이 효소의 활성부위에 cysteine과 histidine 잔기가 필수적이지 않음이 확인되었다. The hydrolysis products formed from birchwood xylan by the action of an alkaline xylanase (CX-III) from alkalophilic Cephalosporium sp. RYM-202 were xylobiose and xylooligosaccharides polymerized with more than 4 sugar molecules. This enzyme was not active on xylobiose but readily attacked xylotriose accumulating xylobiose as a major product. The predominant end-products from xylotetraose by CX-III were xylobiose and xylotriose. These results indicate that the enzyme is typically endo-type xylanase possessing transglycosidase activity. Chemaical modification of CX-III with N-bromosuccinimide revealed that two tryptophan residues per molecule of CX-III were essential for its catalytic activity on xylan. On the other hand, iodoacetamide and diethylpyrocarbonate did not influence the activity of the enzyme, suggesting that cysteine and histidine residues are not involved in the active site of this alkaline xylanase.
박지은,정연재,박준범,김혜영,유영현,이광식,양원태,김도훈,김종민 한국발생생물학회 2019 발생과 생식 Vol.23 No.3
Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR). T2DM is correlated with obesity and most T2DM medications have been developed for enhancing insulin sensitivity. Silk protein fibroin (SPF) from spiders has been suggested as an attractive biomaterial for medical purposes. We generated transgenic rice (TR) expressing SPF and fed it to diabetic BKS.Cg-m+/+Leprdb mice to monitor the changes in blood glucose levels and adipose tissue proteins associated with energy metabolism and insulin signaling. In the present study, the adipocyte size in abdominal fat in TR-SPF-fed mice was remarkably smaller than that of the control. Whereas the adenosine monophosphate-activated protein kinase (AMPK)-activated protein kinase and insulin receptor substrate 1 (IRS1) protein levels were increased in abdominal adipose tissues after TR-SPF feeding, levels of six-transmembrane protein of prostate 2 (STAMP2) proteins decreased. Phosphorylation of AMPK at threonine 172 and IRS1 at serine 307 and tyrosine 632 were both increased in adipose tissues from TR-SPFfed mice. Increased expression and phosphorylation of IRS1 at both serine 307 and tyrosine 632 in adipose tissues indicated that adipocytes obtained from abdominal fat in TR-SPF-fed mice were more susceptible to insulin signaling than that of the control. STAMP2 protein levels decreased in adipose tissues from TR-SPF-fed mice, indicating that STAMP2 proteins were reducing adipocytes that were undergoing lipolysis. Taken together, this study showed that TR-SPF was effective in reducing blood glucose levels in diabetic mice and that concurrent lipolysis in abdominal adipocytes was associated with alterations of AMPK, IRS1, and STAMP2. Increased IRS1 expression and its phosphorylation by TR-SFP were considered to be particularly important in the induction of lipolysis in adipocytes, as well as in reducing blood glucose levels in this animal model.
Streptozotocin 유도 당뇨쥐에서의 Phospholipase A₂, Cyclooxygenase 활성과 Thromboxane 및 Prostacyclin합성
양정아,김성옥,최정화,곽오계,이순재,장현욱 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-
당뇨병에서의 혈전생성 기전에 관련된 주된 요인을 관찰코져 흰쥐를 4주간 사육한 후 streptozotocin(STZ)으로 당뇨를 유발한 후 6일째에 희생하여 당뇨쥐에 있어서의 phospholipase A₂ 활성변화에 따른 조직의 과산화적 손상과 혈소판 응집능 등의 변화를 관찰한 결과는 다음과 같다. 체중증가는 STZ를 투여한 후에는 STZ 투여군에서 현저하게 감소하였다. 식이섭취에 있어 STZ injection 후, DM군은 16% 증가하였다. 식이효율은 STZ injection 후 DM군은 정상군에 비해 유의적으로 감소하였다. 혈청 중의 총 지질과산화물가는 정상군에 비해 DM군은 2.5배 높았다. HDL 중의 TBARS는 정상군에 비해 DM군은 약 1.6배 정도 높았고 LDL 중의 TBARS는 정상군에 비해 DM군에서 4.8배의 높은 증가를 보였다. 혈소판 phospholipase A₂ 활성은 DM군은 정상군에 비해 42% 증가하였다. 혈소판 cyclooxygenase 활성은 정상군에 비해 DM군이 2배 정도 높은 수준이었다. 혈소판 중의 TXA₂ 농도는 정상군과 비교하여 DM군에서 169%로 현저하게 높았고 대동백 PGI₂의 농도는 정상군에 비해 DM군은 낮은 수준을 보였으며 대동맥 PGI₂와 혈소판 TXA₂의 비는 DM군에서 정상군에 비해 55% 낮았다. 결론적으로 STZ 유발 당뇨쥐에 있어서는 혈청 지질과산화물 수준의 증가와 더불어 phospholipase A₂ 활성이 증가되었으며 따라서 cyclooxygenase가 유도하는 AA cascade 활성화에 의해 TXA₂ 생성증가 및 PGI₂/TXA₂ ratio의 감소가 관찰되었다. 이러한 결과는 당뇨병 질환에서 나타나는 동맥경화증, 심혈관계 질환 등의 여러 혈관계의 병리적 현상들이 당뇨 상태에서의 지질대사 이상으로 인한 지질과산화물의 증가와 그의 독성으로 인한 여러 혈소판 관련 인자들의 활성화와 밀접하게 연관되어 나타나는 것을 시사하는 것이라 하겠다. The relation between lipid peroxidation and thrombotic reaction were investigated in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100±10gm were randomly assigned to normal and STZ-induced diabetic group(DM). Diabetes was experimentally induced by intravenous injection of 55mg/kg of body weight of STZ in citrate buffer(pH 4.3) after 4 weeks feeding of basal diet. Animals were sacrificed at the 6th day of diabetic states. Body weight gains were lower in diabetic group after STZ injection. Serum levels of thiobarbituric acid reacting substances(TBARS) that were markedly increased in DM group compared with of normal group. TBARS levles of HDL and LDL were similar patterns to total TBARS of serum. Activities of platelet phospholipase A₂(PLA₂) were higher in diabetic group than those of normal group. Activities of platelet cyclooxygenase were 106% in DM group than normal group. Platelet thromboxane A₂(TXA₂) formation was increased in DM group than normal group. Production of aortic prostacyclin(PGI₂) was lower in diabetic group than that of normal group. PGI₂/TXA₂ ratios were decreased by 55% in DM groups than those of normal group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stess which leads to acceleration of lipid peroxidation and platelet aggregability. In conclusion, accelerating effect of lipid peroxidation and thrombogenesis in diabetic state is regarded to be resulted from enhancement of PLA₂ activity and arachidonic acid metabolism, inhibition of antiaggregating agent and aortic PGI₂ formation.
Selective Cyclooxygenase-2 Inhibitors as Anti-Inflammatory Agents
Chang, Hyeun Wook,Jahng, Yurngdong 영남대학교 약품개발연구소 1998 영남대학교 약품개발연구소 연구업적집 Vol.8 No.-
Basic biology and pharmacology of COX-1 and COX-2 as well as the recent progress in the development of selective COX-2 inhibitors based on structure-activity relationship are summarized.
Inactivation of Phospholipase A₂ by Naturally Occurring Biflavonoid, Ochnaflavone
Chang, Hyeun Wook,Beak, Suk Hwan,Chung, Kwang Won,Son, Kun Ho,Kim, Hyun Pyo,Kang, Sam Sik 영남대학교 약품개발연구소 1995 영남대학교 약품개발연구소 연구업적집 Vol.5 No.-
Ochnaflavone, a medicinal herb product isolated from Lonicera japonica, strongly inhibited rat platelet phospholipase A₂ (IC_(50), about 3μM). Inactivation was concentration and pH dependent (maximum inactivation occurred between pH 9.0 and 10.0). Ochnaflavone inhibited the enzyme by a noncompetitive manner, with the apparent Ki value of 3 × 10^(-5) M. Reversibility was studied directly by dialysis method; the inhibition was irreversible. In addition, the inhibitory activity of ochnaflavone is rather specific against group Ⅱ phospholipase A₂ than group Ⅰ phospholipase A₂(IC_(50), about 20μM). Addition of excess Ca^(2+) concentration up to 8mM did not antagonize the inhibitory activity of ochnatlavone. These results indicate that the inhibition of phospholipase A₂ by ochnaflvone may result from direct interaction with the enzyme.
Chang, Hyeun-Wook,Kwon, Soonhak,Kim, Hengmi,Lee, Kunsoo,Kim, Misuk,Moon, Taechul,Baek, Sukhwan 영남대학교 약품개발연구소 2002 영남대학교 약품개발연구소 연구업적집 Vol.11 No.-
Platelet-activating factor acetylhydrolase was analyzed in cerebrospinal fluid samples taken from children with a variety of neurological conditions (85 patients mean age, 3.8 years) to determine it is involved in the defense mechanism against the toxic effect of inflammatory mediators in the central nervous system. A significant increase in cerebrospinal fluid activity was seen in the patients with meningitis and acute febrile illness in compartison with the control subjects. The activity was also significantly hiher in the patients with meningitis than in the patients with inflammatory neurological diseases. In addition, the biochemical profile of cerebrospinal fluid platelet-activating factor acetylhydrolase was different from other known acetylhydrolases. These findings suggest that cerebrospinal fluid platelet-activating factor acetylhydrolase sctivity may be a sensitive marker of the host response to central nervotis system infections.