Functions of proteins 蛋白质的功能
- Virtually all enzymes are proteins.
- Structural: e.g. collagen and elastin in connective tissue, keratin in skin, hair and nails.
- Contractile proteins: actin and myosin in muscles allow contraction and therefore movement.
- Hormones: many hormones have a protein structure (e.g. insulin, glucagon, growth hormone).
- Transport: for example, haemoglobin facilitates the transport of oxygen around the body, a type of albumin in the blood transports fatty acids.
- Transport into and out of cells: carrier and channel proteins in the cell membrane regulate movement across it.
- Defence: immunoglobulins (antibodies) protect the body against foreign invaders; fibrinogen in the blood is vital for the clotting process.
几乎所有的酶都是蛋白质。
结构性蛋白：如结缔组织中的胶原蛋白和弹性蛋白，皮肤、头发和指甲中的角质蛋白。
收缩性蛋白：肌肉中的肌动蛋白和肌球蛋白允许收缩，从而实现运动。
激素：许多激素具有蛋白质结构（如胰岛素、胰高血糖素、生长激素）。
运输：例如，血红蛋白促进了氧气在身体周围的运输，血液中的一种白蛋白可以运输脂肪酸。
进入和离开细胞的运输：细胞膜上的载体和通道蛋白调节跨膜运动。
防御：免疫球蛋白（抗体）保护身体免受外来入侵；血液中的纤维蛋白原对凝血过程至关重要。
Biochemical test 生物化学试验：
The reagent used to test for proteins is called biuret reagent. It can be used as two separate solutions of copper sulphate and potassium or sodium hydroxide or as a ready-made biuret solution. In either case, a purple colour indicates a positive result.
用于检测蛋白质的试剂被称为生物雷特试剂。它可以作为硫酸铜和氢氧化钾或氢氧化钠的两个独立溶液使用，也可以作为现成的比勒特溶液使用。在这两种情况下，出现紫色表示阳性结果。
知识点回顾：
