Proteins are macronutrients needed to build and repair tissues, produce enzymes and hormones, and support functions from brain health to beautiful skin. Proteins are long chains of smaller units, the amino acids.
The specific sequence and arrangement of amino acids determine the structure and function of each protein. There are twenty different amino acids, combining in various sequences to form proteins.
These sequences determine the specific structure and function of each protein. In living organisms proteins make enzymes to speed up metabolic reactions.
There are countless types of proteins, each with a specialized function. Major categories include:
Enzymes: catalyze biochemical reactions.
Hormones: regulate bodily functions (e.g., insulin).
Antibodies: defend against pathogens.
Structural Proteins: give support and shape (e.g., collagen, keratin).
Transport Proteins: carry molecules (e.g., hemoglobin).
Collagen, best known for skin health, is the most abundant protein in the human body. It provides flexibility and strength to tissues including tendons and ligaments.
How Protein is Created: From Code to Chain
Protein is created with the process of protein synthesis in the ribosomes of cells. It goes through several stages:
Transcription: DNA in the cell's nucleus contains the code for each protein. This code is transcribed into messenger RNA (mRNA). The mRNA then leaves the nucleus to enter the surrounding cytoplasm.
Translation: mRNA carries the genetic instructions to ribosomes, cellular units which can read the code.
Amino Acid Assembly: Transfer RNA (tRNA) molecules bring specific amino acids to the ribosome based on the mRNA code.
Peptide Bond Formation: Amino acids are linked together by peptide bonds, forming a polypeptide chain.
Folding and Structure: The polypeptide chain then folds into a unique three-dimensional structure, determined by the amino acid sequence. Details of folding are essential for the protein's function.
Natural Protein Sources
Suggested dietary allowance for an average sedentary adult is 0.8 grams of protein per kg of body weight. For instance, a person weighing 165 pounds or 75 kg should have 60 grams of protein daily.
Proteins can be classified as complete or incomplete.
Complete Proteins: These contain all nine essential amino acids the body can't produce. Animal sources typically provide these proteins.
meat (beef, pork, poultry)
fish
eggs
dairy products (milk, yogurt, cheese)
Incomplete Proteins: These lack one or more essential amino acids and are often found in plant sources like beans and nuts. Combining foods can create a complete protein intake. Rice and beans together cover all essential amino acids.
legumes (beans, lentils, chickpeas) - peanuts are highest in protein
soy products (tofu, tempeh, edamame)
nuts, seeds, and grains (quinoa, amaranth)
Structures, Properties, and Types of Proteins
The structure of a protein determines its function. There are four levels of protein structure.
Primary: The linear sequence of amino acids. Sequence of amino acids in a polypeptide chain is determined by genetic information.
Secondary: Local folding patterns, like alpha-helices and beta-sheets, form and are stabilized by hydrogen bonds.
Tertiary: This is the three-dimensional shape created from interactions among various side chains of amino acids.
Quaternary: The arrangement of multiple protein subunits. This occurs when two or more polypeptide chains join to create a functional protein.
Proteins have a range of properties, including:
Solubility: Some proteins dissolve in water, while others are insoluble.
Denaturation: Changes in temperature, pH, or exposure to chemicals can disrupt the protein's structure, causing it to unfold and lose its function. This is why cooking alters protein texture. See the Maillard Reaction.
Binding Capacity: Proteins can bind to other molecules, enabling them to perform specific tasks.
Protein is required for:
Growth and Repair: Essential for building and maintaining tissues, including muscles, bones, skin, and organs.
Enzyme Activity: Enzymes accelerate biochemical reactions, facilitating everything from digestion to metabolism. Amylase, an enzyme in saliva and the intestines, begins the digestion of carbohydrates.
Hormone Production: Hormones regulate various bodily processes, including growth, metabolism, and reproduction.
Immune Function: Antibodies, the body's defense system, are proteins.
Fluid Balance: Proteins help regulate fluid balance.
Transport: Transport proteins carry molecules like oxygen and nutrients. Hemoglobin transports oxygen in the blood, while ferritin stores iron in the body.
Environment: Proteins are vital in processes such as decomposing organic matter. Microorganisms and fungi use proteins to break down dead materials, recycling nutrients back to the soil for new growth.
Protein Supplements
Protein supplements, such as whey, casein and soy protein isolates, can be a convenient way to increase protein intake. Supplements come with pros and cons.
Pros:
Convenience: easy to consume and integrate into any diet.
Muscle growth and repair: effective in supporting muscle growth, especially when combined with resistance training.
Weight management: Can promote satiety, aiding in weight loss or maintenance.
Cons:
Potential for overconsumption: excessive protein intake can strain the kidneys.
Digestive issues: some people experience digestive problems from certain supplements.
Cost: supplements can be expensive.
Not a substitute for whole foods: supplements should complement a balanced diet rich in whole foods. Taking supplements without food can inhibit nutrient uptake for vital body functions.
Quality: some supplements may contain additives or fillers which can cause bad reactions. Some countries don't require all ingredients to be listed on packaging.
Facts About Protein
The human body contains tens of thousands of different proteins.
The average adult needs about 0.8 grams of protein per kilogram of body weight daily. This amount may vary based on activity level and individual needs.
The amino acid tryptophan is often associated with sleep due to its role in producing serotonin, a neurotransmitter.
Spider silk is one of the strongest natural materials known, composed primarily of protein.
Deficiency in essential amino acids can lead to a condition called Kwashiorkor, characterized by stunted growth and swelling.
Proteins account for about 15% of human body weight. The largest known protein, titin (connectin), has nearly 30,000 amino acids. Titin is a molecular spring, responsible for passive elasticity of muscles.
Non-Fiction Books:
Fiction Books:
READ: Lora Ley Adventures - Germanic Mythology Fiction Series
READ: Reiker For Hire - Victorian Detective Murder Mysteries