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转酮醇酶(Transketolase,TK)是一种焦磷酸硫胺素(thiamine diphosphate,ThDP)依赖性酶,负责催化磷酸戊糖通路中碳水化合物转化的一个关键反应。此酶属于同源二聚体,在单体间的接触界面上存在两个活性部位。与所有的焦磷酸硫胺素依赖性酶一样,TK活性不仅依赖于焦磷酸硫胺素的存在,还需要二价阳离子。TK存在于所有研究过的生物体中。迄今为止,在人类基因组中,已经确定了一个TK基因和两个TK相似基因,即转酮醇酶基因(TKT)、转酮醇酶样基因-1(transketolase like-1,TKTL-1)和转酮醇酶样基因-2(transketolase like-2,TKTL-2)。据报道,TKTL-1在肿瘤发生中起着重要的作用,同时对肿瘤患者的营养搭配及未来的治疗等方面有着重要的提示。在神经变性疾病、糖尿病和癌症中均发现转酮醇酶样基因变异体的存在,转酮醇酶的活性也有所降低。这些资料为更好地研究这些疾病的发病机理提供了新的线索,并有助于建立新的预防和治疗手段。
Transketolase (TK) is a thiamine diphosphate (ThDP) dependent enzyme that is responsible for catalyzing a key reaction of carbohydrate transformation in the pentose phosphate pathway. This enzyme belongs to homodimers with two active sites at the contact interface between the monomers. Like all pyruvate pyrophosphate-dependent enzymes, TK activity depends not only on the presence of thiamine pyrophosphate but also on divalent cations. TK is present in all studied organisms. To date, one TK gene and two TK-like genes have been identified in the human genome, namely the transketolase like gene (TKT), transketolase like-1 (TKTL-1) and Transketolase like-2 (TKTL-2). It has been reported that TKTL-1 plays an important role in tumorigenesis and has important implications for the nutrition of tumor patients and future treatment. The presence of transketolase-like genetic variants is found in neurodegenerative diseases, diabetes mellitus and cancers and the transketolase activity is also reduced. These materials provide new clues for better understanding the pathogenesis of these diseases and help to establish new preventive and therapeutic tools.