Proteins and Amino Acids

Proteins and amino acids are essential components of the human body, playing a role in many processes. Proteins are composed of various units called "amino acids". There are 20 types of amino acids that make up proteins, two of which are essential for humans and must be obtained from food.

Amino acids are divided into four main classes, namely nonpolar, uncharged polar, acidic, and basic. These classes are based on the properties of the side chains attached to the amino acid�s central carbon atom. Each class has its own unique characteristics.

Proteins have three distinct levels of structure. Primary structure consists of linear sequences of amino acids linked together in a single chain. Secondary structure refers to the formation of hydrogen bonds between a group of amino acids, resulting in helices or beta sheets. The tertiary structure is the overall three-dimensional folding of the entire polypeptide chain, and the quaternary structure is the arrangement of multiple polypeptide chains into a single complex.

Proteins play an important role in the formation of haemoglobin, which carries oxygen around the body. Defects in the structure or production of haemoglobin can lead to disorders such as Thalassaemia and Sickle Cell Anaemia.

Protein also plays a role in nutrition. Nine of the amino acids are essential, meaning that they cannot be synthesized by the body and must be obtained from food. The digestion of protein begins in the stomach and continues in the small intestine, where enzymes break down the proteins into their component amino acids.

Animal sources of proteins such as meat, fish, and eggs contain all nine essential amino acids, while plant sources such as beans, grains, and legumes contain some but not all. Protein deficiencies can lead to a variety of health issues, including stunted growth, impaired immune system, and neurological disorders.

Classification of Amino Acids

Amino acids are the building blocks of proteins and they are classified into four categories: polar neutral, acidic, basic, and special. Polar neutral amino acids are neither positively nor negatively charged. They are also referred to as "hydrophilic" because they dissolve easily in water. Acidic and basic amino acids are respectively charged with a positively or negatively charge. Special amino acids refer to those that have more complex chemical structures than the other three categories.

The most commonly occurring amino acids are alanine, glycine, leucine, isoleucine, valine, threonine, proline, methionine, lysine, phenylalanine, tyrosine, arginine, tryptophan, histidine, glutamine, and asparagine.

Protein Structure

The structure of proteins can be divided into four key components: primary, secondary, tertiary and quaternary. The primary structure of a protein is its sequence of amino acids, linked together by peptide bonds. This sequence is determined by the genetic code of the organism. The secondary structure is an arrangement of the primary structure of amino acids into different shapes such as alpha-helices and beta-sheets. This leads to the tertiary structure, in which the secondary structure is stabilized through interactions between the side chains of the amino acids. Finally, the quaternary structure is the arrangement of multiple protein molecules (subunits) in a specific order to create a functional protein.

The precise structure of a protein is essential for its functioning. Changes in the primary or secondary structure due to denaturation or mutations can lead to changes in the tertiary and quaternary structure, and thus affect the protein�s function.

Clinical Relevance

Proteins, specifically haemoglobin, play an essential role in our bodies. When functioning properly, haemoglobin helps transport oxygen throughout our body. However, some people have genetic mutations which affect the production of haemoglobin. These diseases are known as Thalassaemia and Sickle Cell Anaemia.

Thalassaemia is an inherited condition that results in the lack of ability to produce enough normal haemoglobin. This can lead to anaemia, in which the number of red blood cells or their ability to carry oxygen are reduced. Symptoms can range from mild to severe and can cause fatigue, pale skin, enlarged spleen, and dark urine. Most patients with thalassaemia are able to manage the disease with regular blood transfusions and medication.

Sickle Cell Anaemia is also an inherited condition caused by a mutation in the haemoglobin gene. People with sickle cell anaemia have deformed red blood cells, which makes it harder for them to carry oxygen. This can lead to various health problems such as pain crises, infections, organ damage, and vision or hearing loss. Most people with sickle cell anaemia require regular medical care with treatments including blood transfusions and antibiotics.

It is important to understand the clinical relevance of proteins and haemoglobin in order to diagnose and manage diseases like thalassaemia and sickle cell anaemia.

Proteins and Human Nutrition

Proteins play an essential role in a healthy human diet. They are made up of amino acids, which are the building blocks of proteins. Humans require a total of 20 different types of amino acids for proper protein synthesis. Of those 20, nine are considered essential because our bodies cannot produce them and must come from our diet. These nine essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

These essential amino acids can be found in both animal products, such as meat, dairy, and eggs, and also plant-based foods like legumes, nuts, and seeds. Animal-based proteins tend to have all nine essential amino acids, while plant-based proteins usually lack one or more. It is important to have a balanced diet that provides enough of these essential amino acids to maintain optimal health.

When proteins are consumed, they are first broken down in the stomach by hydrochloric acid and digestive enzymes. This process allows the proteins to be absorbed into the bloodstream as amino acids. From here, they can be used to produce hormones, enzymes, antibodies, and tissues.

Sources of Protein

Proteins are an essential part of our diet and come from a variety of sources. Proteins can be broken down into two main categories: animal and plant proteins. Animal proteins come from both red and white meats, dairy products, and other animal sources. Plant proteins come from sources such as legumes, nuts, and grains.

Animal proteins are often considered to be complete proteins, meaning they provide all 9 essential amino acids that the body cannot make itself. Plant proteins, on the other hand, are typically not complete sources. For people who follow plant-based diets, it is important to ensure that enough protein is consumed from a variety of sources in order to obtain all the essential amino acids.

When people do not consume enough proteins, they may develop nutritional deficiencies which can lead to a range of issues such as poor growth in infants and children, decreased immunity, slow wound healing, anemia, and a decrease in muscle mass. People who are underweight or have had surgery may also need to increase their intake of proteins for recovery.

In summary, proteins from both animal and plant sources are important for overall health and well-being. Eating a balanced and varied diet is key to getting the right nutrients, including proteins, for optimal health.

Key Points

This guide has shared essential factsabout proteins and amino acids such as their structure, function, dietary relevance and sources. Here are the main takeaways to remember:

• Proteins and amino acids are both essential macromolecules that are found in all living organisms.
• Amino acids are classified into four categories; acidic, basic, non-polar and polar.
• Proteins have four levels of structure, primary, secondary, tertiary and quaternary.
• Proteins are critical for proper functioning of the body, especially with regard to haemoglobin.
• Nutrition, digestion and absorption of proteins requires energy, and nine essential amino acids.
• Protein sources can be animal or plant-based, and deficiencies can occur if not properly balanced.