GOOD MORNING

Dr. SHAIKH ANALHAQ A.1ST YEAR

POSTGRADUATEDEPT. OF

ORTHODONTICS

BASICS OF PROTEINS

Proteins are polymers of L-α-amino acids, which are bonded by peptide bonds.

Proteins are made of 20 amino acids linked by peptide bonds

Polypeptide backbone is the repeating sequence of the N-C-C-N-C-C… in the peptide bond

The side chain or R group is not part of the backbone or the peptide bond

Amino acid: Basic unit of protein

COO-NH3+ C

R

HAmino group

Carboxylic acid group

An amino acid

20 Amino acidsGlycine

(G)Nonpolar,hydrophobic

Polar, uncharged

Polar, charged

Proteins play key roles in a living system Three examples of

protein functions Catalysis:

Almost all chemical reactions in a living cell are catalyzed by protein enzymes.

Transport:Some proteins transports various substances, such as oxygen, ions, and so on.

Information transfer:For example, hormones.

Alcohol dehydrogenase oxidizes alcohols to aldehydes or ketones

Alcohol dehydrogenase oxidizes alcohols to aldehydes or ketones

Haemoglobin carries oxygen

Insulin controls the amount of sugar in the blood

General properties of proteinTaste- Tasteless. Hydrolytic or derived

products are bitter.Odor- odorless. On heat drying –burning

odor.

Viscosity- It depends upon the pH, concentration, size and shape of the molecule.

Shape- There is a wide variation In the protein shape. It may be globular, oval, fibrous or elongated .

Elemental composition of protein

5 major elements Carbon- 50-55%

Hydrogen- 6-7.3%

Oxygen- 19-24%

Nitrogen- 13-19%

Sulfur- 0-4%

Classification of proteinsBased on chemical composition:Simple proteins: Contain amino

acids(E.g: Serum albumin, serum globulins, keratin etc)

Conjugated proteins or compound proteins: Conjugated groups + amino acids (E.g.: Egg albumin, hemoglobin, immunoglobulins etc.)

Derived proteins: Partial hydrolysis of simple or compound proteins.(E.g: Gelatin, proteoses & peptones etc.)

Based on shape:Globular proteins: Spherical or

oval E.g.: Hemoglobin, Albumin, and

Enzymes.Fibrous proteins: Elongated and

fiber-like structures. E.g.: Keratin, Collagen etc.

Based on biological function: Catalytic proteins E.g.: Hexokinase, Amylase etc. Defence proteins E.g.: Immunoglobulins as

antibodies Structural proteins E.g.: Keratin, Collagen

Hormonal proteins E.g.: Growth hormone, Insulin etc. Contractile proteins E.g.: Actin, Myosin and

Tropomyosin . Transport proteins E.g.: Serum albumin Storage proteins E.g.: Ferritin Visual proteins E.g.: Rhodopsin & Iodopsin

Membrane proteins E.g.: Sodium potassium pump Hemostatic proteins E.g.: Fibrinogen, Prothrombin. Buffer proteins E.g.: Plasma proteins, Hemoglobin Respiratory proteins E.g.: Hemoglobin, Myoglobin Receptor proteins E.g.: Insulin receptors, Glucagon

receptors, Steroid hormone receptors etc.

Protein structure: Made up of one or more polypeptide

chains.

Proteins with a single polypeptide chain- monomeric proteins.

Proteins with more than one – oligomeric proteins.

Each polypeptide chain in an oligomeric protein is called subunit or monomer.

Examples for oligomeric proteins are hemoglobin, lactate dehydrogenase.

Structural organisation of proteins

1. Primary structure

2. Secondary structure

3. Tertiary structure

4. Quaternary structure

Hierarchical nature of protein structure

Primary structure (Amino acid sequence) ↓Secondary structure （α-helix, β-sheet） ↓Tertiary structure （Three-dimensional

structure formed by assembly of secondary structures）

↓Quaternary structure （Structure

formed by more than one polypeptide chains）

Primary Structure

It is the amino acid sequence (1940) that “exclusively” determines the 3D structure of a protein

20 amino acids – modifications do occur post translationally

Secondary structure

Regular patterns of hydrogen bonding in proteins result in two patterns that emerge in nearly every protein structure known: the -helix and the-sheet.

The location of direction of these periodic, repeating structures is known as the secondary structure of the protein.

α-helix β-sheet

Secondary structures, α-helix and β-sheet, have regular hydrogen-bonding patterns.

α- helix is the most common secondary structure found in proteins.

Most commonly seen in globular protein.

β- pleated sheet is an extended structure.

β- pleated structure is stsbilized by hydrogen bonding.

Tertiary structure Tertiary structure of protein refer to

the further folding of secondary structure of polypeptide chain giving the compact three dimensional conformation.

Tertiary structure results in the orientation of hydrophobic side chain towards the water free interior and the hydrophilic polar groups towards the surface of the protein.

Quaternary structureProtein having more than one

polypeptide chain show more level of higher structure called the quaternary structure.

Quaternary structure refer to the spatial arrangement of the subunits of an oligomeric protein.

Denaturation of proteins The process of disorganization of

native protein structure is called Denaturation.

Denaturation involves the loss of secondary , tertiary and quaternary structures without breaking the primary structure.

Denaturation involves a changes in physical, chemical and biological properties of protein .

Decreases the solubility, increase the precipitiability and increase the viscosity of proteins.

Protein Energy Malnutrition (PEM)

Deficiency disease caused in the infants due to ‘Food Gap’ between the intake and requirement.

It affects children under 5 mostly belonging to the poor underprivileged communities.

PEM is particularly serious during the post-weaning stage and is often associated with infection.

TypesMarasmus

Kwashiorkor

Marasmus Kwashiorkor

MarasmusIt is an overall deficit of food

intake which results from near starvation from with deficiency of protein and non-protein nutrients.

Clinical FeaturesAge – 1 and 3 years

Weight loss

Wasting of subcutaneous fat and muscle

Head of the child seems larger than the body

Very little hair

Ribs of the child are visible

Adomen of the child appears extended and protruding

Child suffers and is more prone to infections

Skin has some pigmentation

KwashiorkorKwashiorkor is another form of

PEM, is it uncommon in the children under one year of age.

It is associated with primary dietary protein deficiency.

Clinical Feature Three essential features of

kwashiorkor are Growth failure

Oedema

Mental changes

Oral ManifestationTongue- Bright reddening, loss of papillae. In kwashiorkor – odema of tongue and

may develop scalloping around lateral margins.

Xerostomia- Mouth becomes dry.

Jaws- Decreased overall growth of jaws.

Teeth- Delayed eruption

Periodontal membrane – Gingiva and periodontal ligament membrane exhibit varying degree of degenration.

Maxillofacial gangrene- Severe infection, spread in mouth from necrotizing gingivitis.

Extra oral- Bilateral angular cheilosis, fissuring of lips.

AmylodosisIt is also called as amyloid

disease.

It is deposition of amyloid in the tissue.

Type A amyloid is a fibrillar protein of unknown origin.

Clinical FeatureCommonly affected kidney,

heart, G.I tract, liver, respiratory tract, skin, eyes, nerves and spleen.

Fatigue, weakness, ankle edema, weight loss.

Purpuric spot

Oral ManifestationThere are difficulty in• Chewing • Swallowing• Speech

Tongue – Enlarged • Mobility of tongue decreased • Presence of yellowish nodules• Impression from the teeth also visible

Gingiva-• Infiltrated• Bluish color• Spongy• Hypertrophied

Salivary gland-Xerostomia may result from

salivary gland involvement.

Bone morphogenic proteinBone morphogenetic proteins form a unique group

of proteins within the transforming growth factor superfamily of genes and have a vital role in the regulation in the bone induction and maintenance.

The activity of bone morphogenetic proteins was first identified in the 1960s, but the proteins responsible for bone induction were unknown until the purification and cloning of human bone morphogenetic proteins in the 1980s, because of their osteoinductive potential.

Bonemorphogenetic proteins have gained a lot of interest as therapeutic agents for treating periodontal defects.

From the times of Hippocrates it has been known that bone has considerable potential for regeneration and repair.

Several decades ago Urist reported the discovery that BMPs induce cartilage, bone formation when implanted intramuscularly in a rodent model.

Bone morphogenetic proteins play essential role in regulation of bone formation and repair.

BMPs are frequently referred to as growth factors, they are now regarded as differentiation factors, because BMPs are involved in morphogenesis and organogenesis.

Periodontal tissue regeneration entails the induction of periodontal ligament, cementum, and alveolar bone.

several studies have shown significant regeneration of the periodontal tissues with the use of BMP.

References Nutrition Science by B Srilakshmi Nutrition and Child Care : A practical

guide by Shanti Ghosh Textbook of Human Nutrition by

Mahtab S. Bamji, N Pralhad Rao and Vinodini Reddy.

Textbook of Biochemistry by Prasad R.M. 2nd edition.

Textbook of Biochemistry by Satyanarayana.

Textbook of Medical Biochemistry by S.S Randhawa.

Textbook of Oral Medicine by Anil Ghoms.

Urist MR. Bone: Formation by autoinduction. Science 1965;150:893‑9.

Urist MR, Strates. Bone Morphogenetic proteins. J Dent Res 1971;50:S1392‑406.

Subramaniam M Rao. Bone Morphogenetic Proteins: Periodontal Regeneration, 2014, November 21 IP: 117.208.128.69.

Jaebum L, Andreas S, Cristiano S, Wikesjo ME. Periodontal Regeneration: Focus on Growth and Differentiation Factors. Dent Clin N Am 2010;54:93‑111.

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