• 한국미생물·생명공학회지
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• 제14권6호
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• pp.441-446
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• 1986

Pseudomonas synxantha A3가 생산하는 세포외 guanine deaminase의 몇가지 성질을 검토하였다. 본 효소의 안정 pH는 6.5-7.5 부근이었으며, 열안정성을 검토하기 위하여 각 온도에서 10분간 처리하였을 때 4$0^{\circ}C$까지 안정하였고 그 이상의 온도에서는 서서히 실활되었다. 또한 pH 8.0의 0.2M potassium phosphate 완충액에 본 효소를 보관하였을 때 실온에서 30일간 안정하였고 alcohol 및 acetone은 본 효소의 안정화에 효과가 없었다. 효소활성을 위한 최적온도 및 pH는 각각 5$0^{\circ}C$와 pH 7-8 부근이었다. 본 효소는 1mM의 Hg$^{++}$, Ag$^+$, Li$^+$에 의해 각각 50%이상 저해되었으며, 0.1mM의 Ag$^+$에 의해서도50%이상 저해되었다. Li$^+$에 의해 저해된 본 효소에 EDTA를 가하였을 때 효소의 활성회복에 효과가 있었다. 본 효소의 활성은 1mM의 pentachlorophenol에 의해 50%, p-CMB에 의해 40%정도 저해되었다. p-CMB에 의해 저해된 본 효소에 thiol compound를 가하였을 때에는, 사용된 시약 중 glutathione이 본 효소의 활성회복에 효과적인 것으로 나타났다.

• Biomolecules & Therapeutics
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• 제31권1호
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• pp.89-96
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• 2023

Uric acid produced by guanine deaminase (GDA) is involved in photoaging and hyperpigmentation. Reactive oxygen species (ROS) generated by uric acid plays a role in photoaging. However, the mechanism by which uric acid stimulates melanogenesis in GDA-overexpressing keratinocytes is unclear. Keratinocyte-derived paracrine factors have been identified as important mechanisms of ultraviolet-induced melanogenesis. Therefore, the role of paracrine melanogenic growth factors in GDA-induced hypermelanosis mediated by uric acid was examined. The relationships between ROS and these growth factors were examined. Primary cultured normal keratinocytes overexpressed with wild type or mutant GDA and those treated with xanthine or uric acid in the presence or absence of allopurinol, H₂O₂, or N-acetylcysteine (NAC) were used in this study. Intracellular and extracellular bFGF and SCF levels were increased in keratinocytes by wild type, but not by loss-of-function mutants of GDA overexpression. Culture supernatants from GDA-overexpressing keratinocytes stimulated melanogenesis, which was restored by anti-bFGF and anti-SCF antibodies. Allopurinol treatment reduced the expression levels of bFGF and SCF in both GDA-overexpressing and normal keratinocytes exposed to exogenous xanthine; the exogenous uric acid increased their expression levels. H₂O₂-stimulated tyrosinase expression and melanogenesis were restored by NAC pretreatment. However, H₂O₂ or NAC did not upregulate or downregulate bFGF or SCF, respectively. Overall, uric acid could be involved in melanogenesis induced by GDA overexpression in keratinocytes via bFGF and SCF upregulation not via ROS generation.