在超高分辨率下,AmpCβ-乳糖酶的脱氧化机制
Yu Chen1, George Minasov, Tomer A Roth
1Department of Pharmaceutical Chemistry, University of California-San Francisco, QB3 Building Room 508D, 1700 4th Street, San Francisco, CA 94143-2550, USA.
Journal of the American Chemical Society
|March 2, 2006
概括
这项研究揭示了AmpCβ-乳糖酶的结构,表明Tyr150在催化过程中被质子化. 这一发现对理解细菌对β-乳糖抗生素耐药性机制产生影响.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 微生物学 微生物学
背景情况:
- β-乳糖酶是赋予细菌对β-乳糖抗生素耐药性的酶.
- AmpCβ-乳酸酶是这种抵抗机制中的关键酶,利用像Ser64,Tyr150和Lys67.7这样的残留物.
研究的目的:
- 为了阐明AmpCβ-lactamase的催化机制.
- 确定关键残留物的作用,特别是Tyr150和Lys67在脱氧化步骤中的作用.
主要方法:
- 在1.07A分辨率的X射线晶体学AmpCβ-lactamase.
- 分析电子密度图以确定质子化状态和键网络.
主要成果:
- 确定了AmpCβ-乳糖酶的高分辨率结构与酸过渡状态模拟物.
- 观察到Tyr150被质子化,其基团捐赠了一个质子来模仿脱水.
- 发现Lys67具有正电荷,与Ser64,Asn152和Ala220相互作用,但与Tyr150.0不同.
结论:
- 结果表明,Tyr150在整个反应中被质子化,不利于铁酸盐的一般基因机制.
- Tyr150可能通过静电相互作用稳定反应中间体.
- 这些发现支持涉及Tyr150作为暂时基或乳酸作为一般基的机制,Lys67发挥了辅助作用.
相关概念视频
Chemiosmosis
Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives many cellular processes. Oxidative phosphorylation involves two processes— the electron transport chain and chemiosmosis.
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Electron Transport Chain
The electron transport chain involves a series of protein complexes on the inner mitochondrial membrane that undergo a series of redox reactions. At the end of this chain, the electrons reduce...
Cell Specific Gene Expression
Multicellular organisms contain a variety of structurally and functionally distinct cell types, but the DNA in all the cells originated from the same parent cells. The differences in the cells can be attributed to the differential gene expression. Liver cells, whose functions include detoxification of blood, production of bile to metabolize fats, and synthesis of proteins essential for metabolism, must express a specific set of genes to perform their functions. Gene expression also varies with...
The Supercomplexes in the Crista Membrane
The mitochondrial cristae membrane is the primary site for the oxidative phosphorylation (OXPHOS) process of energy conversion mediated through respiratory complexes I to V. These complexes have been widely studied for decades, and it has been proven that they form supramolecular structures called respiratory supercomplexes (SC). These higher-order complexes may be crucial in maintaining the biochemical structure and improving the physiological activity of the individual complexes while...
Glycolysis: Preparatory Phase
In cellular metabolism (the complete breakdown of glucose to extract energy), glycolysis is the first step. Glycolysis takes place in the cytoplasm of both prokaryotic and eukaryotic cells. Glucose enters heterotrophic cells in two ways. One method is through secondary active transport, where the transport takes place against the glucose concentration gradient. The other mechanism uses a group of integral proteins called GLUT proteins, also known as glucose transporter proteins. These...
ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
Carbohydrate Catabolism
Carbohydrate catabolism is a fundamental process in cellular metabolism that enables energy extraction from glucose through two primary pathways: cellular respiration and fermentation. Both pathways begin with glycolysis, which operates independently of oxygen availability.Glycolysis: A Shared Starting PointGlycolysis is an oxygen-independent process that breaks down glucose into two molecules of pyruvic acid. During this process, a net gain of two ATP molecules and two NADH molecules is...


