What is the net charge of histidine at pH 8, and 12? For each pH, will histidine migrate toward the anode (+)or cathode (-)when placed in an electric filed?

组氨酸在pH8和12时的净电荷是多少?在这两种pH下，组氨酸当放在电场中时向正极还是向负极移动?

属类：化学及生命科学-化学-化学习题

Mixtures of amino acids are analyzed by first separating the mixture into components through ion-exchange chromatography.

氨基酸的混合物的分析可以首先通过离子交换层析分离为各个组分。

属类：化学及生命科学-化学-化学习题

Amino acids placed on cation-exchange resin with sulfonate groups flow down the column at different rates because of two factors influencing their movement

氨基酸放在带磺基的阳离子交换树脂上以不同的速度流过柱子，影响其流动的两个因素是

属类：化学及生命科学-化学-化学习题

ionic attraction between the –SO3- residues on the column and the charged functional groups on the amino acid residues and hydrophobic interactions between amino acid side chains and the strongly hydrophobic bead of polystyrene resin.

柱子上的–SO3-与氨基酸残基上的带电官能团之间的离子吸引和氨基酸侧链与高度疏水的聚苯乙烯树脂珠之间的疏水相互作用。

属类：化学及生命科学-化学-化学习题

For each pair of amino acids, determine which will be eluted first from the ion-exchange column using a pH 7.0 buffer.

确定下列每对氨基酸在pH7.0的缓冲液中,哪个先从离子交换柱上洗脱下来。

属类：化学及生命科学-化学-化学习题

How many chiral centers does it have?

它有多少个手性中心?

属类：化学及生命科学-化学-化学习题

How many optical isomers?

有多少个光学异构体?

属类：化学及生命科学-化学-化学习题

Draw perspective formulas for the isomers of isoleucine.

画出异亮氨酸异构体的透视式。

属类：化学及生命科学-化学-化学习题

The titration curve of alanine shows the ionization of two functional groups with pKa values of 2.34 and 9.69 correspoding to the ionization of the carboxyl and the protonated amino groups,respectively.

丙氨酸的滴定曲线表明，其两个功能团羧基和质子化的氨基的pKa值分别为2.34和9.69。

属类：化学及生命科学-化学-化学习题

The titration of di-,tri, and larger oligopeptides of alanine also shows that the ionization of only two functional groups, although the experimental pKa values are different. The trend in pKa values is summarized in the table.

丙氨酸的二、三或更大的寡肽的滴定表明，只有两个功能团的解离，尽管其实验pKa值是不同的。pKa值的变化趋势总结于下表中

属类：化学及生命科学-化学-化学习题

Draw the structure of Ala-Ala-Ala. Identify the functional groups associated with pK1 and pK2.

画出Ala-Ala-Ala的结构，标明与pK1和pK2相联系的功能团。

属类：化学及生命科学-化学-化学习题

Why does the value of pK1 increase with each addition of an Ala residue to the oligopeptide?

为什么寡肽每增加一个官能团pK1的值也随之增加?

属类：化学及生命科学-化学-化学习题

Why does the value of pK2 decrease with each addition of an Ala residue to the Ala oligopeptide?

为什么寡肽每增加一个官能团pK2的值也随之降低?

属类：化学及生命科学-化学-化学习题

What is the approximate molecular weight of a protein with 682 amino acid residues in a single polypeptide chain?

一含682个氨基酸残基的单个多肽链的大致分子量是多少?

属类：化学及生命科学-化学-化学习题

A quantitative amino acid analysis reveals that bovine serum albumin (BSA)contains O.58% tryptophan (Mr 204)by weight.

氨基酸的定量分析表明，牛血清白蛋白((BSA)含O.58%的Trp

属类：化学及生命科学-化学-化学习题(分子量为204)

Calculate the minimum molecular weight of BSA (i.e.. assuming there is only one tryptophan residue per protein molecule).

计算其最低分子量(即假定每个蛋白质分子中只有一个Trp)

属类：化学及生命科学-化学-化学习题

Gel filtration of BSA gives a molecular weight estimate of 70，000. How many tryptophan residues are present in a molecule of serum albumin?

BSA的凝胶过滤给出分子量为70，000.BSA分子中有多少个Trp残基?

属类：化学及生命科学-化学-化学习题

What is the net charge of the molecule at pH 3, 8, and 11?

其在pH3,8,和11下的净电荷是多少?

属类：化学及生命科学-化学-化学习题

Estimate the pI for this peptide.

估算此肽的等电点。

属类：化学及生命科学-化学-化学习题

Pepsin is the name given to several digestive enzymes that are secreted-(as larger precursor proteins)by glands that line the stomach.

胃蛋白酶是排列在胃中的腺体以较大前体分泌的数种消化酶的总称。

属类：化学及生命科学-化学-化学习题