Download Utilization of fats and amino acids as fuels

Utilization of fats and amino acids as fuels
• To utilize triglycerides as fuel, they must be:
• Broken down
• Transported
• Activated
• oxidized
• To utilize proteins as fuel, they must be:
• Broken down into amino acids
• Amino group removed (transferred)
• Carbon skeleton will enter pathways at appropriate
points
• Triglycerides broken down by lipoprotein
lipase, which is activated by hormones such
as glucagon, cortisol, growth hormone
• Transported in the blood via serum albumin
• Trapped in the cell by the addition of CoA.
This takes the equivalent of 2 ATPs.
• Transported into the matrix of the
mitochondrion
• Undergoes b oxidation. Chain is shortened
by 2 carbon units (acetyl coA) with each b
oxidation cycle. One NADH + H+ and one
FADH2 produced each time.
• Acetyl coAs go into the TCA cycle, NADH
&FADH to the ET chain
How many turns of b
oxidation would occur for a
12 carbon fatty acid? How
many acetyl CoAs, NADHs
and FADHs would be
produced?
Acetyl CoA
Krebs Cycle
Turns of the b oxidation cycle?
Acetyl CoAs produced?
NADHs and FADH2s produced?
TOTAL ATPs?
• The term glucogenic is used to describe amino acids whose
carbons are converted to glucose by way of the gluconeogenesis
pathway.
• Many amino acids also have pathways which lead to acetylCoA
or to acetoacetyCoA, from which fats or ketone bodies can be
made. These are called ketogenic amino acids. Only two of these
(leucine and lycine) are not also glucogenic. Yes, you can get
fats from proteins, either directly in the case of ketogenic amino
acids or less directly through gluconeogenesis and glycolysis in
the case of glucogenic amino acids.
Proteins are generally used sparingly, and mainly in order to
conserve or replenish blood glucose.
(can be used by the brain as
an alternative to glucose)
Amino Acid
Alanine
Arginine
Asparagine
Aspartate
Cysteine
Glutamate
Glutamine
Glycine
Histidine
Isoleucine
Leucine
Lycine
Methionine
Phenylalanine
Proline
Serine
Threonine
Tryptophan
Tyrosine
Valine
Essential?
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Glucogenic?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Ketogenic?
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
No
Yes
No
No
Yes
Yes
Yes
No