Importance of Proteins in Human Structure and Function

Running head: HUMAN STRUCTURE AND FUNCTION
Human Structure and Function
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1HUMAN STRUCTURE AND FUNCTION
Introduction
Anatomy and physiology entail the structural and functional components of human
body. Macromolecules are the essential part and parcel of the human physiological system.
Comprised of carbohydrates, proteins, lipids and nucleic acids, macromolecules form various
structural and chemical components of our body. Each cell in the body is made up of one or
the other kind of macromolecule. The chosen macromolecule is protein, which is widely
acknowledged as the building blocks of life. Proteins are the major components responsible
for forming enzymes and hormones, constructing blood and muscles, transporting various
materials throughout the body (Buenrostro et al, 2013). The following essay tries to establish
the key points addressing the importance of proteins in the structural reform and functional
abilities of human body.
Discussion
Amino acid residues connected with peptide bonds make up proteins (Whitford,
2013). Chosen proteins for this essay are metalloprotein Haemoglobin and multifunctional
globular protein Actin (Whitford, 2013).
Structure
Each protein is quite specific regarding their functions, and the function of each
protein depends solely on their structural configuration. If the protein’s structure changes in
some unfavourable condition, then that protein can no longer function properly. Generally, all
proteins fall under one of the four structural categories, which are as follows:
1) Primary structure: includes sequence of amino acid chains.

2HUMAN STRUCTURE AND FUNCTION
2) Secondary structure: includes α-helix and β-pleated sheets, which are
constructed with the help of hydrogen bonds between the peptide backbones.
3) Tertiary structure: includes different three-dimensional folds in the proteins
due to side-chain interactions.
4) Quaternary structure: includes proteins which are composed of more than one
amino acid.
Red Blood Cells are comprised of protein pigment haemoglobin molecules which are
responsible for its oxygen carrier function. Each RBC consists of about 250 million
haemoglobin molecules. Haemoglobin has a quaternary structure and it is a protein with
multiple subunits (Gleixner et al., 2016). Each subunit is made up of a protein part and a
prosthetic group such as a metal ion or heme group. The porphyrin ring holds the heme group
in place. The ring is made up of four pyrrole rings. This structure mostly contains alpha
helices which are stabilized by hydrogen bonding. Approximately 150 amino acid residues
make up the two alpha and two beta chains (Gleixner, 2016).
The structure of actin can be globular (like in G-actin) or filamentous (in F-actin) or it
can be a multi-domain protein. It possesses the activity of ATP hydrolysing. A glutamate
residue is also found at the active site of the ATP hydrolytic domain. Together with highly
acidic N-terminus and alkaline C-terminus, it also comprises of 374 amino acid residues
(Blanchoin et al., 2014). Tertiary and super secondary structures have been discovered. It is a
highly conserved protein and is involved in many protein-protein interactions. Actins are
responsible for several significant cellular functional properties including maintenance of cell
shape and form, being a regulator of transcription, to most importantly supporting cell
motility. Actin filaments, in conjunction with myosin, form the basis of muscle contraction.