MindMap Gallery Protein digestion and absorption and amino acid metabolism mind map
This is a mind map about protein digestion and absorption and amino acid metabolism, the nutritional value of protein and digestion, absorption, ammonia metabolism, etc.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
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Protein digestion and absorption and amino acid metabolism
Ammonia metabolism
There are three important sources of blood ammonia
Ammonia can be produced by both amino acid deamination and amine decomposition
Intestinal bacteria produce ammonia
Ammonia secreted by renal tubular epithelial cells mainly comes from glutamine
Ammonia is transported in the blood as alanine and glutamine
Ammonia is transported from skeletal muscle to the liver via the alanine-glucose cycle
Ammonia is transported from tissues such as the brain and skeletal muscles to the liver or kidneys via glutamine
effect
Glutamine is both the detoxification product of ammonia and the storage and transportation form of ammonia.
Glutamine provides the amino group to convert aspartic acid into asparagine
The main metabolic route of ammonia is the synthesis of urea in the liver
Urea is synthesized via the ornithine cycle (urea cycle)
Reaction steps in the ornithine cycle in the liver
NH3, CO2, ATP condense to form carbamoyl phosphate
Carbamoyl phosphate reacts with ornithine to form citrulline
Citrulline reacts with aspartic acid to form argininosuccinic acid
Argininosuccinic acid is cleaved to produce arginine and fumaric acid
Arginine is hydrolyzed to release urea and regenerated into ornithine
overall response
Urea synthesis is regulated by dietary protein and two key enzymes
High-protein meals increase urea production
AGA activates CPS-I to initiate urea synthesis
Argininosuccinic acid synthesis
Impairment of urea production can cause hyperammonemia or ammonia poisoning
Metabolism of individual amino acids
Decarboxylation of amino acids requires decarboxylase catalysis
Glutamic acid decarboxylates to gamma-aminobutyric acid
Decarboxylation of histidine to produce histamine
Tryptophan is hydroxylated and decarboxylated to form 5-hydroxytryptamine
Decarboxylation of certain amino acids can produce polyamines
key enzyme
ornithine decarboxylase
Certain amino acids produce one-carbon units during catabolism
Tetrahydrofolate participates in one-carbon unit metabolism as a carrier of one-carbon units
one carbon unit
An organic group containing one carbon atom produced during the catabolism of certain amino acids
One-carbon units produced from amino acids can be converted into each other
Nutritional Value of Protein and Digestion and Absorption
The metabolic status of proteins in the body can be described by nitrogen balance
nitrogen balance
The relationship between daily nitrogen intake and excretion
The average nitrogen content of protein is 16%
way
ingest
food
discharge
urine and feces
balance
Total nitrogen balance (nitrogen intake = nitrogen output)
normal person
Positive balance of nitrogen (nitrogen intake > nitrogen output)
Children, pregnant women, convalescent patients
Negative nitrogen balance (nitrogen intake < nitrogen output)
Starvation, severe burns, bleeding
Physiological requirements for protein
Nutritional essential amino acids determine the nutritional value of protein
"Bring one or two light-colored books to the group"
Niacin deficiency
nutritional value of protein
Utilization of food protein in the body
Metrics
Types and proportions of essential amino acids in food
Animal protein has relatively high nutritional value
Complementary effects of food proteins
When a variety of proteins with low nutritional value are mixed and eaten, the essential amino acids can complement each other, thereby improving the nutritional value of the protein.
Cereal proteins contain more tryptophan and less lysine
Bean protein contains more lysine and less tryptophan
Exogenous proteins are digested into oligopeptides and amino acids and then absorbed
Proteins are digested into oligopeptides and amino acids in the stomach and small intestine
Physiological significance of protein digestion
Large molecules are converted into small molecules for easy absorption
Eliminate species specificity and antigenicity to prevent allergic and toxic reactions
Proteins are hydrolyzed into peptides and amino acids in the stomach
Proteins are hydrolyzed into oligopeptides and amino acids in the small intestine (the main site of protein digestion)
Digestive effect of pancreatic juice on protease
Protease
Endopeptidase
effect
Specifically hydrolyzes some peptide bonds within proteins
include
Trypsin
chymotrypsin
elastase
exopeptidase
effect
Specific hydrolysis of peptide bonds at the ends of proteins or polypeptides
include
Carboxypeptidase (main)
carboxypeptidase A
carboxypeptidase B
Aminopeptidase
Activation of zymogens in intestinal fluid
Protein digestion by intestinal mucosal cells
Oligopeptidase
Aminopeptidase
dipeptidase
Amino acids and oligopeptides are absorbed through active transport mechanisms
amino acid absorption carrier
Peptide absorption mechanism and significance
Undigested and absorbed proteins become putrid in the lower colon
protein putrefaction
Undigested proteins and unabsorbed digestive products are broken down by intestinal bacteria in the lower colon
product
Mostly harmful
Amine, ammonia, phenol, indole
few useful
fatty acids, vitamins
Gut bacteria produce amines through decarboxylation
pseudoneurotransmitter
Gut bacteria produce ammonia through deamination
Corruption produces other harmful substances
Tyrosine→phenol
Cysteine → hydrogen sulfide
Tryptophan→indole
General metabolism of amino acids
Protein breaks down into amino acids in the body
Proteins degrade at different rates
Half-life (t1/2)
The time required to reduce its concentration to 50% of the starting value
There are two important pathways for protein degradation in eukaryotic cells
Proteins are degraded in lysosomes through an ATP-independent pathway
Features
cathepsin
Degrade exogenous proteins, membrane proteins and intracellular long-lived proteins
Proteins are degraded in the proteasome through the ATP-dependent ubiquitin pathway
Features
Proteasome is responsible for degradation
Dependent on ubiquitin
Ubiquitin
A small molecule protein composed of 76 amino acids, widely present in eukaryotic cells
Primary structure is highly conserved
Degrade abnormal proteins and short-lived proteins
process
ubiquitination
Ubiquitin forms a covalent linkage to proteins selected for degradation, allowing them to be labeled and then degraded by the proteasome
Three enzymes involved in consuming ATP
proteasomal degradation
structure
26S protein complex
20S core particles (CP)
19S Regulating Particles (RP)
Exogenous amino acids and endogenous amino acids constitute the amino acid metabolic pool
Amino acid catabolism begins with deamination
Way
transaminase
transamination
Under the catalysis of aminotransferase, the amino group of an a-amino acid is reversibly transferred to an a-keto acid. The result is that the amino acid is deaminated to form the corresponding a-keto acid, and the original a-keto acid is converted into another amino acid.
type
Aspartate aminotransferase (GOT)/aspartate aminotransferase (AST)
More myocardium
Glutamate aminotransferase (GPT)/alanine aminotransferase (ALT)
Excess liver
Transaminase has the same coenzyme and mechanism of action
coenzyme
Pyridoxal Phosphate
effect
transfer amino
L-glutamate dehydrogenase
L-glutamate dehydrogenase
allosteric enzyme
allosteric inhibitor
ATP,GTP
allosteric activator
ADP, GDP
transamination/deamination/combined deamination
amino acid oxidase
prosthetic base
FMN,FAD
The amino acid carbon chain skeleton can be converted or decomposed
a-keto acid can completely oxidize and decompose and provide energy
way
Tricarboxylic acid cycle and biological oxidation system→CO2 H2O energy
a-Keto acids undergo amination to form nutritionally non-essential amino acids
Pyruvate → alanine
Oxaloacetate → Aspartic acid
a-ketoglutarate→glutamic acid
a-Keto acids can be converted into sugars and lipids