Proteins!!! help!!! pls?

Question

what are the five type of proteins based on junction and five type of protiens based on composition? anyone?

Answer 1

Prtotein functions-

1.Enzymatic catalysis - almost all biological reactions are enzyme catalyzed. Enzymes are known to increase the rate of a biological reaction by a factor of 10 to the 6th power! There are several thousand enzymes which have been identified to date.

2.Binding, transport and storage - small molecules are often carried by proteins in the physiological setting (for example, the protein hemoglobin is responsible for the transport of oxygen to tissues). Many drug molecules are partially bound to serum albumins in the plasma.

3.Molecular switching - conformational changes in response to pH or ligand binding can be used to control cellular processes

4.Coordinated motion - muscle is mostly protein, and muscle contraction is mediated by the sliding motion of two protein filaments, actin and myosin

5.Structural support - skin and bone are strengthened by the protein collagen.

6.Immune protection - antibodies are protein structures that are responsible for reacting with specific foreign substances in the body.

7.Generation and transmission of nerve impulses - some amino acids act as neurotransmitters, which transmit electrical signals from one nerve cell to another. In addition, receptors for neurotransmitters, drugs, etc. are protein in nature. An example of this is the acetylcholine receptor, which is a protein structure that is embedded in postsynaptic neurons.

8.Control of growth and differentiation - proteins can be critical to the control of growth, cell differentiation and expression of DNA. For example, repressor proteins may bind to specific segments of DNA, preventing expression and thus the formation of the product of that DNA segment. Also, many hormones and growth factors that regulate cell function, such as insulin or thyroid stimulating hormone are proteins.

Protein composition -

1.Glycoprotein = +carbohydrate (eg. Blood group antigens on red blood cells.

2.Lipoprotein =+lipids (eg. HDL &LDL inblood plasma).

3.Nucleoproteins = +nucleic acids (eg. in chromatin)

4.Hemoproteins = +heme (egs. haemoglobin and catalase)

5.Metalloproteins =+= +metal (eg. nickel in the enzyme urease)