REFLECTION 9: INTRODUCTION INTO PROTEINS

Hey guys welcome back to my blog!! Today we are moving on to Proteins!! WOOT!! Let’s Begin!

As a part of my Protein introduction we will be looking at basic structures of different amino acids, differences between complete and incomplete proteins, the Ninhydrin & Biuret tests, peptide bond and functional classes of proteins.

Structures & Examples to Learn

Amino Acid                                      

aminogroup

Non-polar, aliphatic R groups

Glycine                                                                                                             

gly

   Alanine

 ala

Proline

  pro

Polar, uncharged R groups

Serine                                                                                                                 

ser

Threonine  

  thr

Cystenine

     cys

Aromatic R groups: Phenylalanine, Tyrosine, Tryptophan

Positively charged R groups: Lysine, Arginine, Histidine

Negatively charged R groups: Aspartate, Glutamate

Essential Amino Acids: Arginine, Histidine, Isoleucine, Valine etc.

Non-Essential Amino Acids: Alanine, Asparagine, Cysteine, Proline etc.

Complete & Incomplete Proteins?

We learnt that a complete protein is one that contains all 10 essential amino acids and is generally found in animal sources; however, an incomplete protein is one that lacks one or more essential amino acids and is generally found in plant sources.

Ninhydrin vs. Biuret

The Ninhydrin test is used to identify Amino Acids. It does this by reacting with the Amino Acid and an imino derivative is formed. A blue/purple colour appears. Note: Proline gives a yellow/orange colour.

ninhydrin01

ninhy

Negative Test (Left) &      Positive Test (Right)

The Biuret test is used to identify Proteins. Here the Cu2+ions in the blue Biuret reagent reacts with the peptide bond of the protein forming a purple complex.

biuret

1495907958_bd1d0a91c4

What is a peptide bond?

A peptide bond is a bond that is formed between two amino acid joining the alpha-carboxyl group of one amino acids to the alpha-amino group of the other. Oligopeptides and polypeptides are formed when peptide bonds join long unbranched chains of amino acids together.

Functional Classes of Proteins

Channels

Controls cell contents

Transport

e.g. haemoglobin in blood

Storage

e.g. ferritin in liver

Enzyme

Catalyze biochemical reactions

Structural

Collagen in skin

Immune Response

Antibodies

Globular, Fibrous & Membrane Proteins

Type of Protein

Structures

Shape

Solubility

Function

Example

Globular

Variety in secondary structure

Spherical shape

Good water soluble

Catalysis, regulation, transport, gene processing

Hemoglobin

Fibrous

One leading secondary structure

Narrow, rod-shaped

Poor water solubility

Structural roles- bone, skin, cytoskeleton

Collagen

Membrane

Inserted through membranes

Multi domain membrane spanning

Poor water solubility

Cell communication- signaling, transport

Photosynthetic reactor center

 

What I attempted to do was give you guys a brief introduction into the Proteins topic. Hope it was helpful! Please like, share and comment 🙂 

References:

Images:

http://www.imgt.org/IMGTeducation/Aide-memoire/_UK/aminoacids/formuleAA/

http://www.daviddarling.info/encyclopedia/A/amino.html

http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch27/ch27-3-3.html

http://www.biosci.ohiou.edu/introbioslab/Bios170/170_2/biuret.htm

http://www.flickr.com/photos/37388341@N00/1495907958/

http://publications.nigms.nih.gov/structlife/chapter1.html

Featured Image:

http://www.unleashedbeasts.com/articles/importance-training-nutrition-supplementation-combined-success/

Youtube- Biochem JM

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