toxins quick flashcards

what are toxins

substances created by plants and animals that are poisonous to humans

produced for predation and defence

what are cyanotoxins

produced by cyanobacteria

(cyclic peptides, alkaloids and lipopolysaccharides)

what are hemotoxins

target and destroy red blood cells

transmitted through the blood stream

what are necrotoxins

cause necrosis (ie death) in the cells they encounter

destroy all types of tissues

what are neurotoxins

primarily affect the nervous systems of animals

what are cytotoxins

are toxic at the level of individual cells, either in a non-specific fashion or only in certain types of living cells

what is apitoxin

honey bee vneom

what are mycotoxins

toxins produced by fungi

what does alpha-amanitin target

targets RNA polymerase II (essential for transcription)

alpha-amanitin binds near the bridge helix of the the enzyme (hydrogen bonds)

hydrogen bonding plays crucical role (e.g hydroxyproline 2 & glu-A822)

what does the binding of alpha-amanitin do

disruption of helix bridge movement

slows down translocation (mvmt along DNA), halting gene expression

what is proamanullin

lacks the key hydroxyl groups involved in hydrogen bonding to bridge helix residue

is ~20,000 times less effective than alpha-amanitin

what is batrachotoxin

member of steroidal alkaloids called batrachotoxins

first discovered in frogs

how does batrachotoxin work

binds and irreversibly opens voltage-gated sodium channels

may bind within the pore of the channel

activity depends on temperature, max 37 degrees

where does batrachotoxin’s electrostatic interactin tkae place

electrostatic interaction between BTX’s protonated tertiary amine and aromatic phenylalanine residues on the sodium channel

what is aromatic-aromatic interactions

attractive, non covalent interactions between aromatic rings

partially pos charged hydrogen atoms on edge of one ring interacts with pi face of another ring

what are the different geometrys of aromatic-aromatic interactions

Sandwich config maximizes overlap of pi system and is LEAST STABLE

what are cation pi interactions

pos charged species bind to pi electron rich regions of aromatics

key in enzyme-substrate or toxin-protein interactions

in proteins, phenylalanine, tyrosine and trptophan are very effective at stabilizing pos charged reaction substrates or intermediates. the aromatic side chains are hydrophobic and cation stabilizing

what are van der waals forces

transient dipoles from fluctuation electron clouds create weak attractions

attraction between two oppositely oreineted dipoles

what are hydrophpobic interactions

non polar molecules cluster together, esp in aqueous environments (eg protein folding)

hydrophobic interactions in proteins

as protein folds, amino acid with a hydrophobic side chain are packed inside the structure, away from the surrounding water molecules

eg ALANINE, LEUCINE, PHENYLALANINE

what is a possible treatment for batrachotoxin

using tetrodotoxin (non competitive inhibitor) or saxitotoxin

both have antagonistic effects to batrachotoxin on sodium flux