MindMap Gallery Protein function and structure
This is a mind map about the function and structure of proteins. The main contents include: the physical and chemical properties of proteins, the relationship between protein structure and function, the molecular structure of proteins, and the molecular composition of proteins.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Protein function and structure
molecular composition of protein
Elemental composition of protein
Main elements: carbon, hydrogen, oxygen, nitrogen, sulfur.
Features: Most proteins have similar nitrogen content, with an average of 16%. Therefore, nitrogen content is commonly used to determine protein content, also called Kjeldahl nitrogen determination method.
The basic building blocks of protein – amino acids
The amino acids that make up human proteins, except glycine, are all L-a amino acids
Classification of amino acids
nonpolar hydrophobic amino acids
polar neutral amino acids
acidic amino acids
basic amino acids
Rare amino acids: selenocysteine, pyrrolysine
Physicochemical properties of amino acids
Sexual dissociation and isoelectric point
Amphoteric dissociation: Amino acids have both acidic a-carboxyl groups and basic a-amino groups, so they have the characteristics of amphoteric dissociation.
Isoelectric point: In a solution with a certain pH, amino acids dissociate into cations and anions to the same extent, and the net charge is zero. At this time, the pH of the solution is the isoelectric point of the amino acid.
Ultraviolet absorption properties: There is a maximum absorption peak at 280nm, so the light absorption value of protein at 280nm can be measured to quantitatively analyze the protein content in the solution.
Ninhydrin reaction: The color of the blue-violet compound is directly proportional to the ammonia produced by the decomposition of amino acids. Based on this, quantitative analysis of amino acids can be carried out.
protein molecular structure
Primary structure: refers to the sequence of amino acids from N-terminus to C-terminus
Secondary structure: refers to the spatial arrangement of the peptide units of a protein polypeptide chain, and does not involve side chains.
a-helix
β-sheet
β-turn
random curls
super secondary structure
secondary structure polymer
Motif: a region with a specific spatial conformation and specific function
tertiary structure
Definition: The relative spatial position of all amino acid residues in the entire peptide chain
domain
Rich in some special amino acids, such as glycine and proline
Relevant to specific functions: such as catalytic activity or binding function
Quaternary structure
There are two or more peptide chains, which refers to the mutual relationship and spatial position between the subunits of multimeric protein molecules.
Chemical bonds: hydrophobic bonds, hydrogen bonds, ionic bonds
Physicochemical properties of protein
Zwitterionic properties
Colloidal properties
Molecular diameter 1~100nm
Provide a hydration film on its surface
Protein surfaces have homogeneous charges
UV absorption peak
The characteristic absorption peak at 280nm can be used for quantitative determination of protein.
protein denaturation
Destroy non-covalent bonds and disulfide bonds without destroying the primary structure
Protein renaturation, precipitation, coagulation
color reaction
biuret reaction
Peptide bond copper sulfate = red or purple
Ninhydrin reaction
Amino acid ninhydrin=blue-purple
protein structure and function relationship
main functions of protein
The biological structure of cells, material transport, catalytic function, information exchange, immune function, maintaining the body's acid-base balance, maintaining osmotic pressure...
Protein primary structure is the basis for higher-order structure and function
Protein function depends on specific spatial structure
Hemoglobin transports oxygen
The combination of the first subunit with oxygen can promote the combination of subsequent subunits with oxygen, which is called a positive synergistic effect.