Protein: The Many Wonderous Forms of Amino Acids
Macronutrient is the name given to fats, carbohydrates and proteins, they are called this because they are the things the body needs in larger quantities. Micronutrients are vitamins and minerals and other things that the body needs, although in smaller quantities. As a fuel, proteins and carbohydrates provide 4 kcal (17kJ) per gram while fats provide 9 kcal (37 kJ) per gram.
Over 10,000 different proteins make up our bodies, researchers have proposed up to several billion different proteins may be necessary for our functioning. Excluding water, 75% of our body is made up of proteins: our hair, our organs and even within our blood – haemoglobin is a type of protein and the antibodies that are part of our immune system are proteins too.
Proteins are made from amino acids. There are at least 20 different types of amino acid and they come together in different ways to create all the proteins in our bodies. Because we don’t store amino acids, our bodies make them in two different ways: either from scratch, or by modifying others. Nine amino acids are called essential —histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine (others are conditionally essential - they are needed when the body is going through changes, for instance pregnancy or fighting an illness). These must be consumed because the body can not modify others to make them. Animal proteins contain all of the essential amino acids, as do edamame, peas, buckwheat, mycoprotein, quinoa and tofu. Rice and beans together makes a complete protein as most beans are low in methionine and high in lysine, while both brown and white rice are low in lysine and high in methionine.
There are some amazing proteins in the body ehich do incredible things, here are two favourites: The SHH gene provides instructions for making a protein known as the Sonic Hedgehog protein. The Sonic Hedgehog protein is involved in cell growth, cell specialization, and the normal shaping of the body in all mammals. In fruit flies with a non-functional sonic hedgehog protein, the bristles on their body which should be normally spaced apart actually clump together to form one patch on the surface. This gives the embryo a “spiny and prickly look” that resembled a hedgehog. An inhibitor of the SHH gene is called Robotnikinin (Dr. Robotnik is the bad guy from Sonic).
Titin (short for Titan protein) is the third most abundant protein in our muscles (after myosin and actin), a human body has approximately 0.5kg of it. It is the largest protein in the body at over 1 micometre (0.001 millimetres) and functions as a molecular spring made up of 244 individually folded protein domains. They way it coils and extends follows very complicated dynamics and it is a very clever protein. And let's just leave it at that today, as I think at least one or two phd's are required to really extend our heads around that one.