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相关概念视频

Ligand Binding and Linkage00:49

Ligand Binding and Linkage

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Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked.  In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence...
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Allosteric Proteins-ATCase01:19

Allosteric Proteins-ATCase

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Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
6.4K
Enzymes02:34

Enzymes

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Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
93.7K
Hydrolysis01:15

Hydrolysis

120.8K
Overview
Hydrolysis is a chemical reaction in which the addition of water breaks down a polymer into its simpler monomer units. For example, peptides break into amino acids, carbohydrates into simple sugars, and DNA into nucleotides. Enzymes often facilitate these processes.
Hydrolysis Reverses Dehydration Synthesis
Complex carbohydrates can be broken down by breaking the bonds between individual sugar units. The reaction breaks a glycosidic bond as water is added to the compound. The...
120.8K
Induced-fit Model01:13

Induced-fit Model

88.6K
Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical...
88.6K
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration02:34

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

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The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
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相关实验视频

Updated: Jan 10, 2026

Micropatterned Surfaces to Study Hyaluronic Acid Interactions with Cancer Cells
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了解氨酸合成酶对基质的结合和利用情况.

Zachery Stephens1, Julia Karasinska1,2, Jochen Zimmer1,3

  • 1University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22903.

bioRxiv : the preprint server for biology
|November 24, 2025
PubMed
概括

氨酸合成酶 (HAS) 使用两步过程将UDP-glucuronic acid (UDP-GlcA) 结合起来,从而提高选择性. 这项研究揭示了HAS如何通过半选择性糖转移合成细胞外基因组件的关键成分氨酸.

科学领域:

  • 生物化学 生物化学
  • 结构生物学 结构生物学
  • 葡萄糖生物学 葡萄糖生物学

背景情况:

  • 氨酸 (HA) 是一个重要的脊椎动物细胞外矩阵多糖.
  • HA在粘附,滑,信号和空间填充方面发挥作用,这对胚胎发生至关重要.
  • 氨酸合成酶 (HAS) 通过聚合UDP激活糖并通过血膜分泌链来合成HA.

研究的目的:

  • 阐明HAS识别和利用UDP-glucuronic acid (UDP-GlcA) 的机制.
  • 了解HAS对子基质结合,催化和产品分泌的方式.
  • 调查HAS.的基质特异性和潜在的杂交性.

主要方法:

  • 单粒子冷电子显微镜 (cryo-EM) 用于确定HAS结构.
  • 生物化学测试以评估酶活性和基质要求.
  • 糖生物学技术分析糖转移机制.

主要成果:

  • 揭示了UDP-GlcA的两步基质结合机制,包括在催化口袋插入之前进行校对姿势.
  • 在活性部位中发现了特定的基本残留物,这些残留物对于检测UDP-GlcA碳酸基组至关重要.
  • 对于UDP-GlcA的转化,HAS需要一个接受糖,这证实了初始化N-乙糖胺的必要性.

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Last Updated: Jan 10, 2026

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Defining Substrate Specificities for Lipase and Phospholipase Candidates

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  • 低温EM检测显示了活性部位的二甲基酸盐,表明HAS可以将GlcA转移到非正规的受体.
  • 结论:

    • 哈斯使用校对机制来增强UDP-GlcA的选择性.
    • 该酶的活性依赖于接受基质,以启动甘氨酸转移.
    • HAS具有半选择性,能够将葡萄糖酸转移到非正规接受器,从而提供了对其生物功能和潜在工程学的见解.