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蛋白質(zhì)簡(jiǎn)介

蛋白質(zhì)（protein）是組成人體一切細(xì)胞、組織的重要成分。蛋白質(zhì)在體內(nèi)轉(zhuǎn)化為脂肪，血液的酸性提高。機(jī)體所有重要的組成部分都需要有蛋白質(zhì)的參與。一般說，蛋白質(zhì)約占人體全部質(zhì)量的18%，最重要的還是其與生命現(xiàn)象有關(guān)。機(jī)體中的每一個(gè)細(xì)胞和所有重要組成部分都有蛋白質(zhì)參與。

氨基酸是蛋白質(zhì)的基本組成單位。它是與生命及與各種形式的生命活動(dòng)緊密聯(lián)系在一起的物質(zhì)。從結(jié)構(gòu)上看，蛋白質(zhì)具有復(fù)雜多樣的空間構(gòu)象，其一級(jí)結(jié)構(gòu)是氨基酸的線性排列順序，而二級(jí)結(jié)構(gòu)如α-螺旋、β-折疊等進(jìn)一步折疊形成三級(jí)結(jié)構(gòu)，多個(gè)亞基組合則構(gòu)成四級(jí)結(jié)構(gòu)。這種精確的結(jié)構(gòu)賦予了蛋白質(zhì)特定的功能。

人體內(nèi)蛋白質(zhì)的種類很多，性質(zhì)、功能各異，但都是由20多種氨基酸（Amino acid）按不同比例組合而成的，并在體內(nèi)不斷進(jìn)行代謝與更新。2025年3月22日，上海交通大學(xué)發(fā)布Venus系列模型，是全球數(shù)據(jù)規(guī)模最大、功能批注標(biāo)簽最多的蛋白質(zhì)數(shù)據(jù)集，為人工智能預(yù)測(cè)蛋白質(zhì)結(jié)構(gòu)和掌握蛋白質(zhì)進(jìn)化模式提供了寶貴資料。

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So far we've covered two of the organic macromolecules carbohydrates and lipids
到目前為止,我們已經(jīng)介紹了兩種有機(jī)大分子:碳水化合物和脂質(zhì)·
Today we'll be talking about proteins
今天,我們將討論蛋白質(zhì)·
Proteins have many uses
蛋白質(zhì)有許多用途·
For example many different proteins are used to form the majority of various body tissues including muscle bone cartilage and hair
例如,許多不同的蛋白質(zhì)用于形成大多數(shù)不同的身體組織,包括肌肉、骨骼、軟骨和頭發(fā)·
Other proteins form specialized channels in cell membranes to let certain substances into or out of the cell
其他蛋白質(zhì)在細(xì)胞膜中形成專門的通道,以便讓特定物質(zhì)進(jìn)入或離開細(xì)胞·
Immunoglobulins also known as antibodies are made of proteins
免疫球蛋白,也叫抗體,是由蛋白質(zhì)組成的·
They are an important part of the immune system
它們是免疫系統(tǒng)的重要組成部分·
Antibody proteins label foreign substances in the body so that the immune system can identify and destroy them
抗體蛋白質(zhì)標(biāo)記體內(nèi)的外來物質(zhì),使免疫系統(tǒng)能夠識(shí)別并摧毀它們·
And all living organisms use regulatory proteins called enzymes to speed up chemical reactions in the body
所有生物體都使用一種叫做酶的調(diào)節(jié)蛋白質(zhì)來加速體內(nèi)的化學(xué)反應(yīng)·
So what are proteins made of
那么,蛋白質(zhì)是由什么組成的呢?
Well all proteins are organic macromolecules which means they're large molecules containing the element carbon
所有蛋白質(zhì)都是有機(jī)大分子,這意味著它們是含有碳元素的大分子·
Like carbohydrates and lipids proteins also contain hydrogen and oxygen
像碳水化合物和脂質(zhì)一樣,蛋白質(zhì)也含有氫和氧·
In addition proteins also contain the element nitrogen
此外,蛋白質(zhì)還含有氮元素·
So what is the structure of proteins
那么,蛋白質(zhì)的結(jié)構(gòu)是什么呢?
Well the protein building block or monomer is something called an amino acid molecule
蛋白質(zhì)的構(gòu)建單元或單體叫做氨基酸分子·
Every amino acid has a particular structure
每種氨基酸都有特定的結(jié)構(gòu)·
They all have the same amino group on one side and a weak acid called a carboxyl group on the other
它們一側(cè)都有相同的氨基,另一側(cè)有一個(gè)叫做羧基的弱酸·
But each amino acid also has a unique side chain called an R group
但每個(gè)氨基酸也有一個(gè)獨(dú)特的側(cè)鏈,叫做R基團(tuán)·
It's made up of one or more atoms that distinguish one amino acid from another
R基團(tuán)由一個(gè)或多個(gè)原子組成,這些原子使得每種氨基酸彼此不同·
There are only 20 possible different R groups so that means there are only 20 possible different amino acids
只有20種可能的R基團(tuán),所以意味著只有20種可能的氨基酸·
A protein is created when amino acids chemically bond to each other
當(dāng)氨基酸通過化學(xué)鍵結(jié)合在一起時(shí),就會(huì)形成蛋白質(zhì)·
The bonds that connect amino acids to make a protein are called peptide bonds
將氨基酸連接在一起形成蛋白質(zhì)的鍵稱為肽鍵·
Small protein molecules are sometimes referred to as protein polymers or peptides
小的蛋白質(zhì)分子有時(shí)被稱為蛋白質(zhì)聚合物或肽·
Like interconnecting toy blocks amino acids can join together to form even longer protein polymers called polypeptides
就像連接的玩具積木一樣,氨基酸可以連接在一起,形成更長(zhǎng)的蛋白質(zhì)聚合物,稱為多肽·
Changing the order of the amino acid sequence or the length of the polypeptide is what creates countless different proteins
改變氨基酸序列的順序或多肽的長(zhǎng)度,便能創(chuàng)造出無數(shù)種不同的蛋白質(zhì)·
In addition a protein's final folded shape is critical to the function it performs
此外,蛋白質(zhì)最終的折疊形狀對(duì)它所執(zhí)行的功能至關(guān)重要·
Heat or chemicals can change a protein's shape but not its amino acid order
熱量或化學(xué)物質(zhì)可以改變蛋白質(zhì)的形狀,但不能改變它的氨基酸順序·
However the change in a protein's shape can cause the protein to lose its functionality
然而,蛋白質(zhì)形狀的改變可能會(huì)導(dǎo)致蛋白質(zhì)失去其功能·
This is called denaturing a protein
這稱為蛋白質(zhì)變性·
Denaturing is usually not reversible
變性通常是不可逆的·
An example of denaturing a protein happens when you fry an egg
變性蛋白質(zhì)的一個(gè)例子就是煎雞蛋時(shí)發(fā)生的情況·
Egg whites are pure protein
蛋白是純蛋白質(zhì)·
If you heat an egg the protein in the egg white becomes denatured
如果加熱雞蛋,蛋白中的蛋白質(zhì)會(huì)發(fā)生變性·
You can see the result of this denaturing as the egg white changes from a clear colored liquid to a white colored solid
你可以看到變性后的結(jié)果,蛋白從透明的液體變成白色的固體·
Even after cooling the egg whites' denatured proteins can't change back to their original shape
即使冷卻后,蛋白質(zhì)變性后的蛋白仍然無法恢復(fù)到原來的形狀·
So the egg white retains its opaque white color and solid form
因此,蛋白保持其不透明的白色和固體形態(tài)·
To sum up proteins are organic macromolecules containing carbon hydrogen oxygen and nitrogen
總結(jié)一下,蛋白質(zhì)是含有碳、氫、氧和氮的大分子·
Enzymes most body tissues and many cells in the immune system are all made up of proteins
酶、大多數(shù)體內(nèi)組織和許多免疫系統(tǒng)細(xì)胞都是由蛋白質(zhì)組成的·
Amino acids are the monomers that make up proteins
氨基酸是構(gòu)成蛋白質(zhì)的單體·
There are only 20 different amino acids
只有20種不同的氨基酸·
Small protein polymer molecules are often called peptides
小的蛋白質(zhì)聚合物分子通常稱為肽·
Long chains of amino acids are also a type of protein polymer called polypeptides
由氨基酸組成的長(zhǎng)鏈也是一種蛋白質(zhì)聚合物,稱為多肽·
Proteins differ in amino acid sequence polypeptide length and folded shape
蛋白質(zhì)在氨基酸序列、多肽長(zhǎng)度和折疊形狀上有所不同·
A protein's folded shape is critical to its function
蛋白質(zhì)的折疊形狀對(duì)其功能至關(guān)重要·