General Review
Proteins are the most fundamental unit in life. It compromises every living thing. Every living things are composed of proteins, enzymes are proteins without which life as we know it, would not exist. Amino acids are the building blocks of proteins. The synthesis of proteins occurs in our body but some must be obtained from our diet, these are called essential amino acids. There are thousands of protein, each with its own specific purposes. A typical protein consists of a carboxy (COOH) functional group, an amine (NH2) group, with a R (or Z as known in chemistry) group. The R group is different from every amino acid, this is what makes each and every amino acid different from one and other. When a carboxy and amine functional group reacts an amide functional group (CONH) is formed and a water molecule is also formed. This is also a condensation reaction.
Protein Source
Protein Sources
Seafoods are very good source of proteins since they sometimes contain less fats such as salmon. Next up is white meat poultry, don't lean towards dark meats since the skin is full of saturated fat, remove them before consumption. Milk, cheese and yogurt as well as being excellent source of protein, they are abundant in calcium and vitamin D. As people are aware that eggs are a very good source of protein, they should also know that they also contain abundant fats as well. Other sources include soy, lean beef and fruits such as apple, banana, cantaloupe, grapes, pears and many more.
Different types of proteins
Our body function because of protein!
There are several types of proteins each with its own especial function:
- Structural
- Enzymes
- Hormones
- Transport
- Protective
- Glycoproteins
Amino Acids
Structure of proteins
All the four stages of a protein
Now let's proceed to some detail analysis of a protein structure. Proteins are linear polymers formed from amino acid monomer. If more amino acids join the growing chain, they form a polypeptide chain linked by peptide bonds between each amino acids. Proteins are formed by condensation reaction and in the process a water molecule is also formed each time an amino acid joins the polypeptide chain. When there is only two amino acids joined together its called a dipeptide. Proteins differ from one another because type, number and sequence of amino acids differ, as well as the redundancy nature of codons (discussed further in DNA section). There are actually 20 amino acid, all with a similar structure but a distinctive change in the (R or Z) group which makes every amino acid unique as they are. There are four different stages which gives rise to the final structure, the different structures are as a result of unique amino acid sequences however its the third shape (tertiary structure) of a protein which determines its properties.
The four stages of making a functional proteins are discussed below!
The four stages of making a functional proteins are discussed below!
Primary Structure
Primary Structure
The first stage of development of proteins starts by the very order of amino acids which are asymbled. This is known as the primary structure. The rest of the stages depend on this stage as the precise order of the amino acids, critically determines the shape of the protein. This stage could be represented by a series of notation like using the short hand symbols which represent individual amino acids.
e.g alanine is represented by Ala.
e.g alanine is represented by Ala.
Secondary Structure
The polypeptide chain then undergoes coiling and folding due to hydrogen bonds between various amino acids. This happens due to the fact that parts of the chain can attract each other, creating particular three-dimensional shapes, by coiling, folding or pleating of sections of a protein. Alpha helix forms, its where the protein chain is coiled like a coiled spring. The "alpha" means that if you look down the length of the spring, the coiling is happening in a clockwise direction as it goes away from you.
Beta pleated sheets also forms, its where the chains are folded so that they lie alongside each other. All of the coiling, alpha helix and beta pleated sheet are hold in balance by hydrogen bond which occurs between the carboxy and amide group.
Beta pleated sheets also forms, its where the chains are folded so that they lie alongside each other. All of the coiling, alpha helix and beta pleated sheet are hold in balance by hydrogen bond which occurs between the carboxy and amide group.
Tertiary Structure
Tertiary Structure
In here there are a lot of interactions which occurs e.g hydrogen bonds, ionic bonds and disulfide bond. Another important interaction is that of the R groups which is the overall factor in influencing the three-dimensional shape of the protein. All of this interactions enables sections of the chains to be folded back on each other in intricate and unique shape which corresponds to its function.
Quaternary Structure
This one is the easy one, its just two or more polypeptide chains linked together. One example is hemoglobin which consists of four polypeptide chains joined together by a variey of hydrogen, covalent and ionic bonds.