Module 14: Amino Acids

Amino acids

are the building blocks of proteins

Amino acids

They belong to an important class of organic compounds that contain both the amino (-NH2) and carboxyl (-COOH) groups

alpha – amino acids

what do you call the 20 most important amino acids?

the alpha – carbon atom

the amino and carboxyl groups are both attached to a single carbon atom, which is called?

prosthetic or variable group (side chain)

Attached to this carbon atom is a ________ in which the 20 standard amino acids differ from one another.

D-(dextrorotatory) or L-(levorotatory)

Amino acids may either be

D-serine

present in the forebrain

D-aspartate

present both in brain and periphery

Amino acids

may have positive, negative or zero net charge

ionic character

The solubility and melting points of amino acids reflect their

polar solvents such as water and ethanol

Amino acids are soluble in

nonpolar such as benzene, hexane, or ether

Amino acids are insoluble in

ALIPHATIC AMINO ACIDS

possess hydrocarbon side chains arranged in chain-like structures otherwise known as the monoamino – monocarboxylic acids

monoamino – monocarboxylic acids

other name for ALIPHATIC AMINO ACIDS

AROMATIC AMINO ACIDS

possess the benzene ring (C6H6) in their side chains

HYDROXYAMINO ACIDS

possess the hydroxyl group (-OH) in their side chains

ACIDIC AMINO ACIDS

possess an additional carboxyl group (-COOH)

AMIDES OF ACIDIC AMINO ACIDS

possess an amide group (-CONH2) in their side chains

BASIC AMINO ACIDS

possess an additional amino group (-NH2) in their side chains

SULFUR-CONTAINING AMINO ACIDS

possess a thiol group (-SH) in their side chains

IMINO ACIDS

they have a cyclic imino group in their structure

NON – POLAR (HYDROPHOBIC) AMINO ACIDS

They prefer to contact with one another than water.

NON – POLAR (HYDROPHOBIC) AMINO ACIDS

Generally found buried in the interior of proteins, where they can associate with one another and remain isolated from water.

POLAR (HYDROPHILIC) AMINO ACIDS

They attached to water and are often found on the surfaces of protein.

Polar, neutral amino acids

have R groups that have a high affinity for water but are not ionic

Negatively charged amino acids

have ionized carboxyl group in their side chains

Positively charged amino acids

have a positive net charge of + 1 because their side chains contain a positive group

ESSENTIAL AMINO ACIDS

are those that cannot be synthesized by the body and are required in the diet

NON – ESSENTIAL AMINO ACIDS

are those that can be synthesized by the body and need not be included in the
diet

Histidine

is an essential amino acid for infants but not for adults

Cysteine and Tyrosine

are considered to be semi-essential amino acids

Cysteine and Tyrosine

They are required by premature infants and adults who are ill

aminoaciduria

result from impaired ability to transport defects typically result in the excretion of urine of increased amounts of one or more amino acids

Genetic defects in the metabolism of amino acids can

result in severe illness, if left untreated, result in mental retardation and early death.

ten essential L--amino acids

Human diets must contain adequate quantities of ______ to maintain health.

hormones

L- amino acids in low-molecular weight peptides play additional roles as?