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1、日志生物化学习题库1看看明星们！有几个像我！生物化学名词解释杂七杂八 2008-12-26 13:45 阅读213评论0 字号： 大大 中中 小小 绪论生物化学是利用化学的原理与方法去探讨生命本质的一门科学，主要研究生物体的分子结构与功能(尤其是生物大分子在生命活动中的作用）、物质代谢与调节、 信息传递等。Biochemistry is the science concerned with the various molecules that occur in living cells and organisms and with their chemical reactions. 生物大分子
2、（macromolecule）：A molecule having a molecular weight in the range of a few thousand to many millions， such as proteins, nucleic acids and polysaccharides. 生物大分子（macromolecule ），是由某些基本结构单位按一定顺序和方式连接所形成的多聚体(polymer)，分子量一般大于104。 代谢途径（metabolic pathway): The sum of the enzyme-catalyzed reactions that oc
3、cur in a living organism. 蛋白质的结构与功能 蛋白质(protein)是由许多氨基酸(amino acids)通过肽键(peptide bond)相连形成的高分子含氮化合物。 Protein： A macromolecule composed of one or more polypeptide chains. Each polypeptide chains has a characteristic sequence of amino acids linked by peptide bonds. The molar mass is usually above 100,
4、000 氨基酸（amino acid）： An organic acid with an -carbon atom linked to a carboxylic acid, an amino group, a hydrogen atom, and a side chain (the R group). Twenty different amino acids are the building blocks of proteins. 酸性氨基酸Glu，Asp；侧链基团在中性溶液中解离后带负电荷的氨基酸。 碱性氨基酸His，Arg，Lys；侧链基团在中性溶液中解离后带正电荷的氨基酸。 中性氨基酸
5、侧链基团在中性溶液中不发生解离，因而不带电荷的氨基酸。 氨基酸分子带有相等正、负电荷时，溶液的pH值称为该氨基酸的等电点（pI）。 肽 是由氨基酸通过肽键缩合而形成的化合物。 peptide: Two or more amino acids covalently joined by peptide bonds. 肽键(peptide bond)是由一个氨基酸的a-羧基与另一个氨基酸的a-氨基脱水缩合而形成的化学键。 peptide bond： A covalent linkage formed between the -carboxyl group of one amino acid and
6、the - amino group of another. Also known as an amide bond. 由十个以内氨基酸相连而成的肽称为寡肽(oligopeptide) 由更多的氨基酸相连形成的肽称多肽(polypeptide)。 polypeptide: A long chain of amino acids linked by peptide bonds; the molecular weight is generally less than 10,000. 肽链中的氨基酸分子因为脱水缩合而基团不全，被称为氨基酸残基(residue)。 多肽链(polypeptide cha
7、in)是指许多氨基酸之间以肽键连接而成的一种结构。 carboxyl-terminal residue：The amino acid residue in a polypeptide chain with a free -carboxyl group. 生物体内具有一定生物学活性的肽类物质称生物活性肽。重要的有谷胱甘肽、神经肽、肽类激素等。 蛋白质的二、三、四级结构均属于空间结构，即构象(conformation) Conformation. The three-dimensional arrangement adopted by a molecule, usually a complex m
8、acromolecule. Molecules with the same configuration can have more than one conformation.蛋白质分子多肽链中氨基酸的排列顺序称为蛋白质的一级结构(primary structure)。 primary structure ：In a polymer, the sequence of amino acids and any interchain and intrachain disulfide bonds of a protein. This sequence is specified by genetic i
9、nformation. 蛋白质的二级结构(secondary structure)是指蛋白质分子中某一段肽链的局部空间结构，也就是该段肽链主链骨架原子的相对空间位置，并不涉及氨基酸残基侧链的构象。secondary structure：The localized conformation of a protein. As the polypeptide chain folds, it forms certain localized arrangements of adjacent amino acids . 参与肽键的6个原子Ca1、C、O、N、H、Ca2位于同一平面，Ca1和Ca2在平面上所
10、处的位置为反式(trans)构型，此同一平面上的6个原子构成了所谓的肽单元 (peptide unit) 。peptide unit: The six atoms of the peptide group (Ca1、C、O、N、H、Ca2) lie in a single plane, with the oxygen atom of the carbonyl group and the hydrogen atom of the amide nitrogen trans to each other. The peptide CON bonds are unable to rotate freel
11、y because of their partial double-bond character. Rotation is permitted about the NOC- and the C-OC bonds. -螺旋 (helix) 是多个肽键平面通过碳原子旋转，相互之间紧密盘曲成稳固的右手螺旋的构象形式。 - helix: A helical conformation of a polypeptide chain, usually right-handed, with maximal intrachain hydrogen bonding; one of the most common
12、secondary structures in proteins. -折叠是由若干肽段或肽链排列起来所形成的相当伸展的片层构象。 Beta-sheet: A sheetlike structure formed by the interaction between two or more extended polypeptide chains. It is the extended conformation. -转角(-turn)是多肽链180回折部分所形成的一种二级结构。 The b-turn, which makes a tight 180-degree turn, involves fo
13、ur amino acids. The first amino acid is hydrogen-bonded to the fourth. b-turn occur primarily at protein surfaces and often contain proline or glycine. 无规卷曲（random coil）是指多肽链主链部分形成的无规律的卷曲构象。在许多蛋白质分子中，可发现二个或三个具有二级结构的肽段，在空间上相互接近，形成一个特殊的空间构象，被称为模体(motif)。 蛋白质的三级结构(tertiary structure)是指整条肽链中全部氨基酸残基的相对空间
14、位置，也就是整条肽链所有原子在三维空间的排布位置。 tertiary structure ：The overall three-dimensional conformation of a protein in its native folded state. 大分子蛋白质的三级结构常可分割成一个或数个球状或纤维状的区域，折叠得较为紧密，各行使其功能，称为结构域。 Domain：A segment of a protein that has a discrete function or conformation. At the protein level, a domain can be as
15、small as a few amino acid residues or as large as half of the entire protein. 分子伴侣 （ molecular chaperon）帮助新生多肽链正确折叠的一类蛋白质。1. 可逆地与未折叠肽段的疏水部分结合，防止错误折叠。2. 与错误折叠的肽段结合，诱导其正确折叠。3. 对蛋白质分子中二硫键的正确形成起重要作用。 The molecular chaperones are large, multisubunit proteins that accelerate the folding process by providing a protected environment where polypeptides fold into native conformations and form quaternary structures. 蛋白质的四级结构（quaternary structure)就是指蛋白质分子中亚基的立体排布，亚基间的相互作用与接触部位的布局。 亚基(subunit)就是指参与构成蛋白质四级结构的、每条具有三级结构的多肽链。 quaternary structure：In proteins containing more
