Proteins · 蛋白质
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| amino acid/əˈmiːnəʊ ˈæsɪd/ | 氨基酸 | ān jī suān |
| peptide bond/ˈpeptaɪd bɒnd/ | 肽键 | tài jiàn |
| polypeptide/ˌpɒlɪˈpeptaɪd/ | 多肽 | duō tài |
| disulfide bond/ˈdaɪsəlfaɪd bɒnd/ | 二硫键 | èr liú jiàn |
| globular/ˈɡlɒbjʊlə/ | 球状 | qiú zhuàng |
| fibrous/ˈfɪbrəs/ | 纤维状 | xiān wéi zhuàng |
| haemoglobin/ˌhiːməˈɡləʊbɪn/ | 血红蛋白 | xuè hóng dàn bái |
| collagen/ˈkɒlədʒn/ | 胶原蛋白 | jiāo yuán dàn bái |
The body's master molecules
- Proteins do almost every job in the body — enzymes, oxygen carriers, structure.
- They are all built from the same 20 small units, amino acids 氨基酸.
- Their precise 3-D shape is what lets them work.
身体的主控分子
- 蛋白质几乎做身体里的每一项工作——酶、氧气载体、结构。
- 它们都由相同的 20 个小单元构成,氨基酸(amino acids)。
- 它们精确的三维 形状 才是让它们工作的东西。
Amino acids and the peptide bond 肽键
- Every amino acid has the same core: an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen, and a variable R group (side chain) — the R group is what differs.
- Two amino acids join by condensation: a peptide bond forms and one water is removed.
- Many joined make a polypeptide 多肽; hydrolysis (adding water) breaks peptide bonds.
Two amino acids join by condensation, forming a peptide bond and releasing one water
氨基酸和肽键
- 每个氨基酸都有相同的核心:一个 氨基(amino group)(–NH₂)、一个 羧基(carboxyl group)(–COOH)、一个氢,和一个可变的 R 基团(侧链)——R 基团是不同之处。
- 两个氨基酸通过 缩合(condensation) 连接:一个 肽键(peptide bond) 形成,移除一个水。
- 许多连接起来构成一个 多肽(polypeptide);水解(hydrolysis)(加水)断开肽键。
两个氨基酸通过缩合连接,形成一个肽键并释放一个水
The bond that joins two amino acids is a: · 连接两个氨基酸的键是一个:
Amino acids join by peptide bonds, formed by condensation with the loss of one water molecule. · 氨基酸通过肽键连接,该键通过缩合形成,失去一个水分子。
Four levels of structure
| Level | Meaning |
|---|---|
| primary | the order of amino acids in the chain |
| secondary | local shapes — α-helix and β-pleated sheet — held by hydrogen bonds |
| tertiary | the whole chain folded into a precise 3-D shape |
| quaternary | two or more polypeptide chains joined into one protein |
- Tertiary shape is held by R-group interactions: hydrophobic interactions, hydrogen bonds, ionic bonds, and strong disulfide bonds 二硫键.
The four levels of protein structure
四个层次的结构
| 层次 | 含义 |
|---|---|
| 一级(primary) | 链中氨基酸的 顺序 |
| 二级(secondary) | 局部形状——α-螺旋 和 β-折叠片——由氢键保持 |
| 三级(tertiary) | 整条链折叠成一个精确的三维形状 |
| 四级(quaternary) | 两条或更多多肽链连接成一个蛋白质 |
- 三级形状由 R 基团相互作用保持:疏水相互作用、氢键、离子键,和强的 二硫键(disulfide bonds)。
蛋白质结构的四个层次
The four levels of protein structure · 蛋白质结构的四个层次
Build a protein up one level at a time: sequence → local shapes → a folded 3-D shape → several chains joined. · 一次一个层次地构建一个蛋白质:序列 → 局部形状 → 一个折叠的三维形状 → 几条链连接。
Match each level of protein structure to its meaning. · 把蛋白质结构的每个层次与它的含义配对。
Primary = sequence; secondary = local helix/sheet; tertiary = overall 3-D fold; quaternary = multiple chains. · 一级 = 序列;二级 = 局部螺旋/片;三级 = 整体三维折叠;四级 = 多条链。
Put the levels of protein structure in order, simplest first. · 把蛋白质结构的层次按顺序排列,最简单的在前。
Each level builds on the one before: sequence → local shape → 3-D fold → several chains. · 每个层次建立在前一个之上:序列 → 局部形状 → 三维折叠 → 几条链。
A protein made of two or more polypeptide chains joined together has a ______ structure. · 一个由两条或更多多肽链连接在一起构成的蛋白质有一个 ______ 结构。
Quaternary structure is two or more chains in one protein — e.g. haemoglobin (four chains). · 四级结构是一个蛋白质中的两条或更多链——例如血红蛋白(四条链)。
Strong disulfide bonds are among the R-group bonds that hold a protein's tertiary 3-D shape. · 强的二硫键是维持一个蛋白质三级三维形状的 R 基团键之一。
Tertiary shape is held by hydrophobic interactions, hydrogen bonds, ionic bonds and strong disulfide bonds between R groups. · 三级形状由 R 基团之间的疏水相互作用、氢键、离子键和强的二硫键保持。
Globular 球状 vs fibrous 纤维状
- Globular proteins fold into a rounded, usually soluble shape and do active jobs — e.g. haemoglobin 血红蛋白, which has a quaternary structure (4 chains, each with a haem group holding an iron atom) and carries 4 oxygen molecules.
- Fibrous proteins form long, insoluble strands for support — e.g. collagen 胶原蛋白, three chains wound into a triple strand, cross-linked into strong fibres.
球状与纤维状
- 球状(Globular) 蛋白质折叠成一个圆形的、通常 可溶 的形状,做活跃的工作——例如 血红蛋白(haemoglobin),它有一个四级结构(4 条链,每条带一个握着一个铁原子的 血红素(haem) 基团),携带 4 个氧分子。
- 纤维状(Fibrous) 蛋白质形成长的、不可溶 的链以支撑——例如 胶原蛋白(collagen),三条链缠绕成一个三股,交联成结实的纤维。
Which correctly pairs a protein with its type? · 哪个正确地把一个蛋白质与它的类型配对?
Haemoglobin is a soluble globular protein; collagen is an insoluble fibrous structural protein. · 血红蛋白是一个可溶的球状蛋白质;胶原蛋白是一个不可溶的纤维状结构蛋白质。
Haemoglobin can carry four oxygen molecules because it has: · 血红蛋白能携带四个氧分子,因为它有:
Four polypeptide chains, each holding a haem group with an iron atom, give four oxygen-binding sites. · 四条多肽链,每条握着一个带铁原子的血红素基团,给出四个氧结合位点。
You've got it
- amino acid = –NH₂ + –COOH + H + R group; join by peptide bond (condensation)
- primary (order) → secondary (helix/sheet) → tertiary (3-D fold) → quaternary (≥2 chains)
- globular = rounded, soluble, functional (haemoglobin, 4 chains + haem/iron, carries O₂)
- fibrous = long, insoluble, structural (collagen, triple strand, cross-linked)
你掌握了
- 氨基酸 = –NH₂ + –COOH + H + R 基团;通过 肽键 连接(缩合)
- 一级(顺序)→ 二级(螺旋/片)→ 三级(三维折叠)→ 四级(≥2 条链)
- 球状 = 圆形、可溶、有功能(血红蛋白,4 条链 + 血红素/铁,携带 O₂)
- 纤维状 = 长、不可溶、结构性(胶原蛋白,三股,交联)