enzymes non specification

• vitamins

  
• Cyanide

  potassium cyanide (KCN) is highly toxic because it inhibits aerobic respiration ; and catalase

  • when ingested, KCN is hydrolysed to produce hydrogen cyanide, a very toxic gas that can readily dissociate into H+ and CN- ions
  • the CN- ions bind irreversibly to an enzyme found in mitochondria and inhibit the final stage of aerobic respiration

  →because of final stage inhibition, earlier stages cannot run and aerobic respiration stops
• Snake Venom

  venom of green mamba snake contains a chemical that inhibits the enzyme acetylcholinesterase (AChE)

  →this enzyme is important at neuromuscular synapses to break down the neurotransmitter, acetylcholine (ACh)

  if this enzyme is inhibited, the ACh stays attached to receptors on muscle membrane and keeps muscle contracted

  • this causes paralysis, as movement depends on muscles being able to contract and relax alternately - if the muscles involved in breathing are paralysed then victims die from suffocation
• Aspirin

  drug been used for over 3000 years

  Professor John Vane and his team discovered that salicylic acid binds to enzymes that catalyse formation of prostaglandins - thus prevents the formation of prostaglandins that are cell-signalling molecules produced by cells when tissues are infected or damaged
• Aspirin 2

  • Prostaglandins make nerve cells more sensitive to pain and increase swelling during inflammation
  • Aspirin can reduce the risk of blood clots forming in blood vessels, and many people take a low dose to reduce the risk of strokes

  →however, children under 12 years old should not take it as aspirin can damage stomach lining
• ATPase inhibitors

  extracts from purple foxglove leaves have been used for centuries to treat heart failure and atrial arrhythmia (abnormal beat rate of the atria)

  • the chemicals are now identified ascardiac glycosides also known as digitalis, digitoxin, digitalin or digoxin

  → they inhibit the sodium potassium pump in the cell membranes of heart-muscle cells, and allow more calcium ions to enter cells - calcium ions increase muscle contraction, and strengthens heartbeat
• ACE inhibitors

  medical drugs that inhibit the angiotensin converting enzyme (ACE),which normally operates in a metabolic pathway that ultimately increases your blood pressure

  • used to lower blood pressure in patients with hypertension who cannot take beta-blockers
  • used to treat heart failure - a low dose is given at first, and patient's blood pressure is checked in case it falls too low
  • to minimise risk of second heart attack on a stroke in patients who have suffered a myocardial infarction
• Protease inhibitors

  used to treat some viral infections e.g. amprenavir and ritonavir

  • they prevent the replication of the virus particles within the host cells by inhibiting protease enzymes so that the viral coats cannot be made

  → these inhibitors often inhibit viral protease enzymes by competitive inhibition
• Nucleoside Reverse Transcriptase Inhibitors

  many of antiviral drugs, such as zidovudine and abacavir, is used to treat patients who are HIV-positive are nucleoside reverse trancriptase inhibitors

  • they inhibit enzymes involved in making DNA using the viral RNA as a template