lectins

1. Presented By:
SyedaTamannaYasmin
1st semseter
M.Sc Microbiology
ID: DU2017MSC0130

2.  Lectins are a special class of proteins widely distributed in
nature, which selectively recognized and reversibly bind to
carbohydrates and glycoconjugates through their binding
sites.
 These are the proteins, which can be detected through
haemagglutination assays, interact with different
carbohydrates present in cell surfaces.
 Lectins are generally classified according to their structure,
specificity for carbohydrates and species location.
 Lectins are ubiquitous in nature and are found in many foods.
 Some foods such as beans and grains need to be cooked or
fermented to reduce lectins content, but the lectins
consumed in a typical balanced diet are not harmful.

5. • Lectins serve many different biological functions
in animals, from regulation of cell to adhesion
to glycoprotein synthesis and the control of
protein levels in the blood.
• They also may bind soluble extracellular and
intercellular glycoprotein.
• Some lectins are found on surface of mammalian
liver cells that specifically recognize galactose
residues.
• They help mediate the first-line defense against
invading microorganisms in animals.

6.  The function of lectins in plants is still uncertain. Once
thought to be necessary for rhizobia binding, this proposed
function was ruled out through lectin-
knockout transgene studies.
 The large concentration of lectins in plant seeds decreases
with growth, and suggests a role in plant germination and
perhaps in the seed's survival itself.
 The binding of glycoprotein on the surface of parasitic cells
also is believed to be a function.
 Several plant lectins have been found to recognize non-
carbohydrate ligands that are primarily hydrophobic in
nature. It has been suggested that these interactions may be
physiologically relevant, since some of these molecules
function as phytohormones.

7. • It is hypothesized that
some hepatitis C viral
glycoprotein attach to C-type
lectins on the host cell surface
(liver cells) for infection.

8.  Involved in various biological functions.
 They are used in medicine and medical
research.
 Use in studying of carbohydrates recognition by
protein.
 Use as biochemical tool
 Detection, isolation and identification of
complex carbohydrates.
 Also sometimes applied in clinical fields.
 Separation of cells.

9.  Ingesting lectins can cause
flatulence.
 Consuming legumes and grains in
their raw form can even result in
nausea, diarrhea and vomiting.