Proteins Flashcards
Describe the process of protein digestion
Protein digestion is the most complex digestive process with multiple steps to denature dietary protein, render it into amino acids and transport the amino acids via multiple gut transporters.
Some proteins are naturally absorbed whole or partially digested - such as wheat gluten - that can provoke an allergic reaction e.g. coeliac disease
Illustrate the respective utilisation of nitrogen obtained from proteins in the diet
We make and break-down over 300 grams of protein daily, recycling approximately two thirds of the amino acids in normal conditions.
The broken down amino acids are stripped of carbon for fuel. Many amino acids make non-protein products such as neurotransmitters.
What is pellagra?
What causes it?
Sustained eating of corn causes pellagra, and it is attributable to _niacin deficiency and a lack
of tryptopha_n (a niacin precursor). Spanish peasants and negro labourers in USA
were particularly prone to pellagra.
Plants do not have blood and nervous systems - they have less proteins and different proteins compared to humans.
Plant diets lack the same amino-acid content of meat
Particularly, corn lacks any tryptophan
What are Maillard reactions?
Maillard Reactions occur when a Schiff base forms between a reducing sugar (glucose) and amines from protein.
The Maillard reactions create flavour and change the color. It is also the browning reaction of toast
Maillard reaction occurs most readily at around 150° C to 300° C
What is transamination?
Transamination is the two way conversion between amino acids and keto acids
e.g pyruvate and alanine
Branched chain amino acids (valine, leucine and isoleucine) transaminate in muscles, but have no proven role as a sports performance enhancement.
What is the alanine cycle?
Alanine is produced by muscles to carry excess nitrogen to the liver (or less so kidneys)
In the liver, the alanine is split into pyruvate and excess nitrogen which processed into urea.
How much uric acid and urea do humans excrete everyday?
0.6g of uric acid everyday
30 g of urea everyday (~15g of nitrogen)
What leads to gout?
The underlying condition that causes gout is hyperuricemia. Formation of uric acid crystals in joints causes arthritis
High levels of uric acid in blood is caused by (1) excess uric acid production, or (2) kidney failure to excrete the uric acid effectively. For people who create too much uric acid, the cause is usually genetic
Many gout patients have a combination of overproduction and under-excretion of uric
acid. This combination happens with drinking alcohol, especially beer. The more alcohol
the patient drinks, the worse the problem. Alcohol both raises uric acid levels in the body
and impairs the kidneys’ ability to excrete the buildup
Gout can can be treated with
allopurinol.
