What are proteins?

Enzymes,antibodies,many Enzymes,antibodies,many hormones,and substances that help the hormones,and substances that help the blood to clot,are all proteins. blood to clot,are all proteins.

Protein is the material basement of Protein is the material basement of life,that is,we can’t have life without life,that is,we can’t have life without protein.protein.

There is protein in cells of organisms There is protein in cells of organisms and all important compositions.and all important compositions.

Protein accounts for 16%~~20% of Protein accounts for 16%~~20% of people’s weight. people’s weight.

Where are they from?

Where are the amino acid from?Where are the amino acid from? Of the basic set of 20 amino acids, Of the basic set of 20 amino acids,

there are 8 that human beings there are 8 that human beings cannot synthesize. cannot synthesize.

Proteins!

Protein Denaturation

How they work?

Enzymes Enzymes The best-known role of proteins in The best-known role of proteins in

the cell is as enzymes, which the cell is as enzymes, which catalyze chemical reactions. catalyze chemical reactions. Enzymes are usually highly specific Enzymes are usually highly specific and accelerate only one or a few and accelerate only one or a few chemical reactions. Enzymes carry chemical reactions. Enzymes carry out most of the reactions involved out most of the reactions involved in metabolism, as well as in metabolism, as well as manipulating DNA in processes such manipulating DNA in processes such as DNA replication, DNA repair, and as DNA replication, DNA repair, and transcription. transcription.

Many proteins are involved in the Many proteins are involved in the process of cell signaling and signal process of cell signaling and signal transduction. Some proteins, such transduction. Some proteins, such as insulin, are extracellular proteins as insulin, are extracellular proteins that transmit a signal from the cell that transmit a signal from the cell in which they were synthesized to in which they were synthesized to other cells in distant tissues. Others other cells in distant tissues. Others are membrane proteins that act as are membrane proteins that act as receptors whose main function is to receptors whose main function is to bind a signaling molecule and bind a signaling molecule and induce a biochemical response in induce a biochemical response in the cell. the cell.

Cell signaling and ligand binding

Structural proteins

Structural proteins confer stiffness Structural proteins confer stiffness and rigidity to otherwise-fluid and rigidity to otherwise-fluid biological components. Most biological components. Most structural proteins are fibrous structural proteins are fibrous proteins. proteins.

Other proteins that serve structural Other proteins that serve structural functions are motor proteins such functions are motor proteins such as myosin, kinesin, and dynein, as myosin, kinesin, and dynein, which are capable of generating which are capable of generating mechanical forces. mechanical forces.

How much do we need?

In our daily life, we generally get In our daily life, we generally get protein from meat, egg, milk , nuts protein from meat, egg, milk , nuts and soy-based foods(soybean is and soy-based foods(soybean is better). better).

The quality of protein which The quality of protein which comes from animals is better than comes from animals is better than plant's. plant's.

A piece of meat that has the same size A piece of meat that has the same size as a playing card contains about as a playing card contains about 30~35g protein, a cup of milk contains 30~35g protein, a cup of milk contains about 8~10g protein. So a piece of about 8~10g protein. So a piece of meat, a cup of milk, some beans, some meat, a cup of milk, some beans, some vegetables and some rice can provide vegetables and some rice can provide with enough protein(60~70g).with enough protein(60~70g).

It is better that 1/3 protein is animal It is better that 1/3 protein is animal protein and 2/3 is plant protein. protein and 2/3 is plant protein.

Because human body cannot storage Because human body cannot storage protein , we should get some protein protein , we should get some protein each three meals. each three meals.