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1.
酰尿输出型蚕豆有一定程度合成和同化酰脲的能力(刘承宪和黄维南1987a),蚕豆叶片尿囊素酶(B-ALNase)和酰脲输出型大豆叶片尿囊素酶(S-ALNase)(Thomas等1983)不同,是热敏感的(刘承宪和黄维南 1987b)。我们进一步分离和纯化B-ALNase,并作了初步的鉴 相似文献
2.
蚕豆根、茎和叶含有0.31~0.70 μmol酰脲·g~(-1)FW,并受结瘤和生长发育的影响。摘除正在生长的器官可观察到同腋位叶片酞脲含量暂时升高现象。 叶片中酰脲主要是尿囊酸。尿囊素酶和脲酶活性分别为0.30 μmol尿囊酸·g~(-1)FW·h~(-1)和0.19 μmol NH_3·g~(-1)FW·h~(-1)。尿囊酸含量和尿囊素酶活性日变化相似,只是后者峰值比前者出现早。 相似文献
3.
An unusual allantoinase from Dolichos biflorus has been purified 62-fold. The purified enzyme has an unusual pH activity profile with a shoulder at pH 4 and a peak at pH 7.5. This is due to a single enzyme which does not need metal ions for activation. In the fully reduced state the enzyme exhibits a single sharp peak at 7.5; when it is not in the sulfhydryl form (in the fully oxidized SS form?) the enzyme shows a single pH optimum at pH 4. Km values for (±)-allantoin were 5.5 mM at pH 4 and 1.43 mM at pH 7.5. Allantoinase activity has been demonstrated in the resting seed, and increased linearly with time during the first 5 days of seedling growth. 相似文献
4.
Vigna radiata seedlings germinated in the presence of Mn2+ show an unusual increase in allantoinase activity which is proportional to Mn2+ concentration up to 5 mM. Though Mn2+ is not an activator for V. radiata allantoinase, it specifically protects allantoinase against thermal as well as papain-catalysed inactivation. Evidence is presented to show that the primary effect of Mn2+ is a protective one, both in vitro and in vivo, and that this is reflected in the observed enhancement of allantoinase activity in Mn2+ grown seedlings. That this unusual effect of Mn2+ is a specific one is indicated by the lack of a similar effect with Mg2+. Cu2+ is shown to destabilize V. radiata allantoinase in vitro as well as in vivo. 相似文献
5.
The end product of purine metabolism varies from species to species. The degradation of purines to urate is common to all
animal species, but the degradation of urate is much less complete in higher animals. The comparison of subcellular distribution,
intraperoxisomal localization forms, molecular structures, and some other properties of urate-degrading enzymes (urate oxidase,
allantoinase, and allantoicase) among animals is described. Liver urate oxidase (uricase) is located in the peroxisomes in
all animals with urate oxidase. On the basis of the comparison of intraperoxisomal localization forms, mol wt, and solubility
of liver urate oxidase among animals, it is suggested that amphibian urate oxidase is a transition form in the evolution of
aquatic animals to land animals. Allantoinase and allantoicase are different proteins in fish liver, but the two enzymes form
a complex in amphibian liver. The subcellular localization of allantoinase and allantoicase varies among fishes. Hepatic allantoinase
is located both in the peroxisomes and in the cytosol in saltwater fishes, and only in the cytosol in freshwater fishes. Hepatic
allantoicase is located on the outer surface of the, peroxisomal membrane in the mackerel group and in the peroxisomal matrix
in the sardine group. Amphibian hepatic allantoinase-allantoicase complex is probably located in the mitochondria. On the
basis of previous data, changes of allantoinase and allantoicase in molecular structure and intracellular localization during
animal evolution may be as follows: Fish liver allantoinase is a single peptide with a mol wt of 54,000, and is located both
in the peroxisomes and in the cytosol, or only in the cytosol. Fish liver allantoicase consists of two identical subunits
with a mol wt of 48,000, and is located in the peroxisomal matrix or on the outer surface of the peroxisomal membrane. The
evolution of fishes to amphibia resulted in the dissociation of allantoicase into subunits, and in the association of allantoinase
with the subunit of allantoicase. This amphibian enzyme was lost by further evolution. 相似文献
6.
Geun-Joong Kim Dong-Eun Lee Hak-Sung Kim 《Biotechnology and Bioprocess Engineering》2002,7(3):155-162
The cyclic amidohydrolase family enzymes, which include allantoinase, dihydroorotase, dihydropyrimidinase and (phenyl)hydantoinase,
are metal-dependent hydrolases and play a crucial role in the metabolism of purine and pyrimidinein vivo. Each enzyme has been independently characterized, and thus well documented, but studies on the higher structural traits
shared by members of this enzyme family are rare due to the lack of comparative study. Here, we report upon the expression
inE. coli cells of maltose-binding protein (MBP)- and glutathione S-transferase (GST)-fused cyclic amidohydrolase family enzymes, facilitating
also for both simple purification and high-level expression. Interestingly, the native quaternary structure of each enzyme
was maintained even when fused with MBP and GST. We also found that in fusion proteins the favorable biochemical properties
of family enzymes such as, their optimal pHs, specific activities and kinetic properties were conserved compared to the native
enzymes. In addition, MBP-fused enzymes showed remarkable folding abilityin-vitro. Our findings, therefore, suggest that a previously unrecognized trait of this family, namely the ability to functional fusion
with some other protein but yet to retain innate properties, is conserved. We described here the structural and evolutionary
implications of the properties in this family enzyme. 相似文献
7.
《Bioscience, biotechnology, and biochemistry》2013,77(11):2558-2560
Allantoinase and allantoicase are known to form a complex in amphibian liver. In this study, a new type of allantoinase that did not form a complex with allantoicase was found in the amphibian liver. Purified enzyme had a molecular mass of about 44 kDa both in SDS-PAGE and gel-filtrations. The enzyme cross-reacted with anti-sardine allantoinase polyclonal antibody, and it weakly cross-reacted with anti-bullfrog allantoinase polyclonal antibody. 相似文献
8.
The presence of a stable allantoinase in Lathyrus sativas and its de novo synthesis at a maximal rate in the first 48 hr of germination have been demonstrated. The plumule and radicle together exhibited highest enzyme activity. L. sativas allantoinase has been purified nearly 35-fold. The purified enzyme was optically active around pH 7.5, did not require any metal ion for activity and exhibited a Km of 2·56 mM for (±)-allantoin, and an activation energy of 5·6 kcal/mol. Unlike other plant allantoinases, the L. sativus enzyme is highly specific for (±)-allantoin and is shown to be a sulfhydryl enzyme which apparently exists in a stable form in vivo obviating the need for added sulfhydryl compounds for maximal activity. 相似文献
9.
蚕豆叶片尿囊素酶热敏感,在30℃的半衰期是50min。缺底物时预处理10min,半失活温度是41.5℃。甘油能提高其热稳定性,在30%甘油保护下,15℃和25℃之间的活化能是14 644J mol~(-1)(3.5 keal/mol)。 相似文献
10.