L-PIPECOLIC ACID OXIDASE--ENZYMOLOGY, GENETICS, AND PEROXISOMAL DISORDERS

L-哌啶酸在全身性过氧化物酶体疾病中蓄积， Zellweger综合征和脑卒中发作性肾上腺脑白质营养不良，以及 其他几组进行性神经系统疾病患者。 虽然大多数人认为L-哌啶酸氧化存在缺陷， 一般性过氧化物酶体障碍的儿童， 缺陷未知。 由于L-哌啶醇的明显神经作用 酸及其代谢产物，L-哌啶酸的这种升高可能与 在这些疾病中发现的深度智力迟钝。 分解代谢 用于L-哌啶酸氧化的酶最近已被纯化至接近 已经产生了该酶的多克隆抗体。 该项目将重点对这种纯化酶进行进一步研究。 主要重点将包括研究分布和相对活动 脑组织中酶的研究，对共价黄素的进一步研究- 含有部分蛋白质，酶的克隆和测定 其遗传特征，以及鉴定和研究 有酶缺陷的病人。 这项工作将产生信息， 正常的L-哌啶酸氧化途径，也将有助于阐明 过氧化物酶体中L-哌啶酸氧化缺陷的病因 疾病，以及那些罕见的患者与其他形式的 高哌啶酸血症 对这种蛋白质的进一步研究将使我们能够 确定酶是否含有典型的羧基末端氨基 参与酶靶向过氧化物酶体的酸性序列。 利用抗体和部分氨基酸序列信息， 应该有可能产生这种酶的cDNA克隆。 这些克隆 将成为未来研究的工具，以表征高哌啶酸血症， 基因水平，并找到一个基因组克隆， 如上游环节的特点，调节和同步 可以区分过氧化物酶体酶的产生。 此外该 L-哌啶酸点缺陷患者的鉴定 氧化将是特别有启发性的，因为任何代谢和 在这些患者中发现的神经学变化只能归因于此 缺损

L-Pipecolic acid accumulates in the generalized peroxisomal disorders such as Zellweger syndrome and neonatal-onset adrenoleukodystropy, as well as in several other groups of patients with progressive neurologic diseases. While a defect in L-pipecolic acid oxidation is recognized in the majority of children with generalized peroxisomal disorders, the cause of this defect is unknown. Because of the apparent neurologic role of L-pipecolic acid and its metabolites, this elevation of L-pipecolic acid may be related to the profound mental retardation found in these diseases. The catabolic enzyme for L-pipecolic acid oxidation has recently been purified to near homogeneity and a polyclonal antibody to the enzyme has been produced. This project will focus on further studies with this purified enzyme. Major foci will include a study of the distribution and relative activity of the enzyme in brain tissues, further study of the covalent flavin- containing portion of the protein, cloning of the enzyme and determination of its genetic characteristics, and identification of and studies of patients with defects in the enzyme. This work will yield information on the normal L-pipecolic acid oxidation pathway and will also help elucidate the etiology of the L-pipecolic acid oxidation defects in peroxisomal diseases, as well as in those rarer patients with other forms of hyperpipecolic acidemia. Further studies with the protein will allow us to identify whether the enzyme contains the typical carboxyl terminal amino acid sequences involved in the targeting of enzymes to the peroxisomes. With both the antibody and the partial amino acid sequence information, it should be possible to produce cDNA clones for the enzyme. These clones will be tools for future studies to characterize hyperpipecolic acidemia at the genetic level and to find a genomic clone, so that common characteristics such as upstream segments that regulate and synchronize peroxisomal enzyme production may be distinguished. In addition, the identification of patients with a point defect of L-pipecolic acid oxidation would be particularly enlightening because any metabolic and neurologic changes found in such patients can only be attributed to this defect.