Are peptide bonds protein specific? Please give an explanation

In high school biology, it should be, but pay attention to the substance, biuret (that is, h2n-co-nh-co-nh2 formed by two urea removing one molecule of ammonia), can react with biuret reagent in purple, (protein and polypeptides above two peptide bonds can react purple), so the peptide bond structure is not protein-specific, at least biuret (h2n-co-nh-co-nh2) has it. As long as the organic compounds containing the -nh-co- structure have peptide bonds, but they are not called peptide bonds, they are called amide bonds, so we should think that since they are called peptide bonds, they should be the -nh-co- structure contained in proteins or polypeptides, and there are also -nh-co- structures in other organic compounds, but they are not called peptide bonds, so peptide bonds are protein-specific.

I think it's peculiar. Because only amino acids are called peptides when they make up proteins, and the corresponding peptide bonds are specific to proteins.

But the essence of a peptide bond is an amide bond. Urea contains this bond, but one thing, experimentally proven, urea does not undergo a double shrinkage reaction.

Actually, there is, but it is uncommon, two molecules of urea remove one molecule of ammonia to form biuret (biuret), which has a complete peptide bond.

No, two molecules of urea strip one molecule of ammonia to form biuret (biuret), which has a complete peptide bond.

The peptide bond is willAmino acidsIt is formed by the dehydration and condensation of amino and carboxyl groups between moleculesChemical bonds, because the condensation product is called a peptide, it is called a peptide bond. A peptide bond refers to the carbonyl group in an amide group.

The lone pairs on the nitrogen atom in the adjacent c-n bond together form a three-center, four-electron delocalized bond.

The peptide bond is in a trans configuration. Since peptide bonds cannot rotate freely, cis-trans isomerism can occur in the plane of peptide bonds.

phenomenon, O and H or two C's connected to a C-N bond. The atoms are generally in a more stable trans configuration.

1.The lone pair of electrons on the nitrogen atom has a distinct conjugation effect with the carbonyl group.

2.The bond length of the C—N bond in the peptide bond is longer than the C=N bond and shorter than the adjacent C-N single bond. The C-N bond in the peptide bond has a partial double bond nature and cannot rotate freely.

3.The four atoms that make up the peptide bond are in the same plane.

4.In most cases, peptide bonds exist in a trans structure.

Peptide chainsThe relationship with peptide bonds is a tandem relationship. The peptide bond is on the peptide chain, and the peptide bond makes up the peptide chain.

The peptide chain is made up of multiple amino acids.

A chain-like structure formed by being connected to each other. Belonging to one of the chemical substances, amino acids pass through the carboxyl group.

After dehydration with amino groups, it is condensed to form a product that presents a one-dimensional stretch form. Peptide bonds refer to the chemical bonds that connect individual amino acids to each other when amino acids are linked to each other to form proteins.

Introduction to peptide chains

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Meaning of peptide chain and peptide bond:

Peptide chain: It is a chain-like structure formed by multiple amino acids linked together. It is one of the chemical substances, and amino acids are dehydrated by carboxyl and amino groups and condensed to form a product that presents a one-dimensional stretch form.

Peptide bonds refer to the chemical bonds that connect individual amino acids to each other when amino acids are linked to each other to form proteins.

The relationship between the two:

A peptide chain is formed by a number of amino acids linearly linked by peptide bonds. To use an analogy, a row of people holding hands together forms a human chain, each of them is like an amino acid, and when the hands of the two of us are connected together, it is like a peptide bond.

Therefore, the relationship between the two can be elaborated as follows: every two amino acids are connected to each other to form a peptide bond, and a chain structure containing multiple peptide bonds formed by the interconnection of multiple amino acids is called a peptide chain.

The main thing is:Peptide bondsThe C-N single bond in has about 40 double bond properties, while the C=O double bond has 40 single bond properties. This leads to two important results:

First, the imino group of the peptide bond has no obvious tendency to dissociate and protonation in the pH 0-14 range.

Second, the single C-N bond in the peptide bond cannot rotate freely, so that the white matter can be folded into various three-dimensional conformations.

This is the theoretical basis of the peptide plane, which is the basis of higher order structures.

Principle of formation. consists of one amino acid.

The carboxyl group and the amino group of another amino acid are removed by a molecule of water to form an amide bond, which is also called a peptide bond.

Peptide bonds have special properties. From the point of view of bond length, the peptide bond length (between c—n single bond (and double bond), has the nature of partial double bond, and cannot rotate freely.

From the point of view of bond angle, the angle between the bond and the bond in the peptide bond is 120°. Therefore, the six atoms (CN, C, O, N, H, CA) connected to the peptide bond are always in the same plane, forming a rigid "peptide bond plane", also known as the "amide plane" or peptide unit. In the peptide unit, hydrogen and oxygen atoms attached to c—n.

with two carbon atoms.

It is inversely distributed.

The peptide bond in the protein molecule is mainly formed at the C-position of the amino acid, and many amino acid units are connected by peptide bonds to become polypeptide chains. Peptide bonds are protein structures.

in the main chemical bonds.

In fact, the polypeptide chain is the basic backbone of proteins.

The peptide bond in the protein molecule is made up of oneAmino acidsThe -amino group and another amino acidCarboxylFormative.

The chemical formula of the peptide bond is co-nh, and the peptide bond is an amide bond formed by the dehydration and condensation of the -carboxyl group of one molecule of amino acids and the -amino group of one molecule of amino acids, i.e., the second of -co-nh-"-"represents the key.

Amino acids are linked to polypeptide chains by peptide bonds, which are the main covalent bonds in protein molecules.

The nature is relatively stable.

Although it is a single bond, it has the nature of a partial double bond, which is difficult to rotate freely and has a certain rigidity, so the formation of the peptide bond plane includes the spatial position of 6 atoms of C O, N-H and 2 C at both ends of the peptide bond in a relatively close plane, and the side chain R of the adjacent two amino acids forms a trans configuration, thus forming a complex spatial structure of peptide bond and peptide chain.

Let the number of peptide bonds of the protein be x, and the protein is composed of n peptide chains, so the number of amino acids is x+n, according to the sum of the molecular weights of all amino acids in the protein is equal to the molecular weight of the protein plus the molecular weight of the peptide bond formed during protein synthesis, the equation is obtained

x+n)a=b+x*18

Calculate: x=(b-an) (a-18).

The key to this problem is that the number of amino acids is equal to the number of peptide bonds plus the number of peptide chains, and the peptide bonds are formed to remove a molecule of water.

Proteins are divided into carboxyl and amino groups, and one carboxyl group and one amino group are dehydrated and condensed to form a peptide bond, that is, if there are n amino acids, there are n-1 peptide bonds.

Peptide chains: Look at at least a few amino or carboxyl groups.

Peptide bonds: There are n amino acids in a peptide chain, and the peptide bond n-1

Correct Answer: A Analysis: The peptide bond is formed by the dehydration and condensation of the -carboxyl group of one molecule of amino acids and the -amino group of one molecule of amino acids, i.e., -co-nh-.

A peptide bond is an amide bond formed by the dehydration and condensation of the carboxyl group of an amino acid and the amino group of an amino acid, i.e., -co-nh-.

Amino acids are linked by peptide bonds to form polypeptide chains. It is the main covalent bond in the protein molecule, and its properties are relatively stable. Although it is a single bond, it has the property of a partial double bond, which is difficult to rotate freely and has a certain rigidity, so it forms a peptide bond plane.

The covalent bond (—co-NH—) formed by the dehydration and condensation of the -amino group of one molecule of amino acids and the -carboxyl group of another molecule of amino acids is called peptide bond. Two molecules of amino acids are condensed into dipeptides, which still have free -amino and -carboxyl groups, and can also be condensed with other amino acids to form tripeptides by peptide bonds.

The same reaction can be carried out in succession, and tetrapeptide and pentapeptide ..... are formed sequentiallyPeptides that are usually composed of less than 10 amino acids are called oligopeptides; More amino acids can be linked to form polypeptides, and ammonia bending and base acids are connected to each other to form long chains, called polypeptide chains.

Peptide bonds are the special structural traces that are ubiquitous in proteins and are also the characteristic structures of proteins.

Proteins are made up of one amino acid after another, each of which is composed of four parts, a carboxyl group, an amino group, an R group, and a hydrogen atom, which are connected to the same carbon atom and are divided into L and D types according to the different spatial configurations.

The carboxyl and amino groups between the two amino acids can undergo dehydration and condensation under the action of enzymes to form a peptide bond structure.

a.It is formed by the dehydration of the -amino group of one amino acid and the -carboxyl group of another amino acid.

b.Both the amino and carboxyl groups of amino acids form peptide bonds.

c.The side-chain carboxyl group of glutamic acid is formed by dehydration of the -amino group of another amino acid.

d.The side defects of lysine are formed by dehydration of the chain amino group with the -carboxyl group of another amino acid.

e.It is formed by the dehydration of the side chain of one amino acid - amino group and the side chain of another amino acid - carboxyl group.

Correct Answer: a