Melanin

DEFINITION, TYPES OF MELANIN, IMPACTS ON SKIN ,PATHWAY FOR MELANIN PRODUCTION,FUNCTIONS OF MELANIN , PRODUCTION IN MICROORGANISMS, APPLICATIONS

1. MELANIN PRODUCTION M.MEENAKSHI, DEPT OF MICROBIOLOGY, SRI RAMAKRISHNA CAS FOR WOMEN, COIMBATORE

2. MELANIN PRODUCTION Melanin  is  produced  through a multistage chemical process known as melanogenesis , where the oxidation of the amino acid tyrosine is followed by polymerization. The  melanin  pigments are  produced  in a specialized group of cells known as melanocytes UV-A rays from the sunlight penetrate into the lower layers of the epidermis and  trigger  the melanocytes to  produce  more  melanin .   Melanin  is  produced  as a defence mechanism. Sunlight is the major  cause  of increased  melanin production . Other factors include hormonal imbalances, aging and inflammation processes.

3. MELANIN PRODUCTION IN BACTERIA & FUNGI

4. MELANIN IMPACT ON SKIN

5. PATHWAY OF MELANIN SYNTHESIS

6. TYPES OF MELANIN Melanin also acts as an antibiotic and free radical sink. Due to its wide range of functions, melanin is expressed in several areas of the human body, including the skin, hair, eyes and the brain. However, melanin’s specific roles within these tissues are poorly elucidated. The major types of melanin are: Pheomelanin – an orange to red pigment, expressed in the hair and skin. Low protective properties against DNA damage induced by UV radiation. Eumelanin – a brown to black pigment, expressed in the hair and skin. Higher protective properties against DNA damage induced by UV radiation. Neuromelanin – expressed in several regions in the brain. Its loss is associated with several neurological disorders.

7. MELANIN PRODUCTION Melanocytes are mainly restricted to the basal layer of the epidermis where they form an ‘epidermal melanin unit’, consisting of one melanocyte, around 36 keratinocytes, and one Langerhans cell Most bacterial melanins are formed due to transformations of aromatic amino acids such as tyrosine. Additionally , some  bacteria  can  produce melanin  from malonyl -CoA in a process catalyzed by polyketide synthases . The autopolymerization of this unstable precursor leads to the formation of brownish HPQ  melanin  

8. In MICROORGANISMS… The production of black pigments in bacteria was discovered more than a century ago and related to tyrosine metabolism. However, their diverse biological roles and the control of melanin synthesis in different bacteria have only recently been investigated. The broad distribution of these pigments suggests that they have an important role in a variety of organisms. Melanins protect microorganisms from many environmental stress conditions, ranging from ultraviolet radiation and toxic heavy metals to oxidative stress. Melanins can also affect bacterial interactions with other organisms and are important in pathogenesis and survival in many environments. Bacteria produce several types of melanin through dedicated pathways or as a result of enzymatic imbalances in altered metabolic routes . The control of the melanin synthesis in bacteria involves metabolic and transcriptional regulation, but many aspects remain still largely unknown. The diverse properties of melanins have spurred a large number of applications, and recent efforts have been done to produce the pigment at biotechnologically relevant scales.

9.   MAIN BIOLOGICAL FUNCTIONS OF MELANINS.

10. ENGINEERED ORGANISMS .

11. APPLICATIONS? Uv protection Medical surgical dressings Synthetic pigments alternatives Cosmetics