Amino Acids Organic compounds containing both the amine -NH 2 and carboxyl -COOH functional groups. Amine e.g. CH 3 CH 2 NH 2 ethylamine Carboxylic acid.

Slides:



Advertisements
Similar presentations
Geometrical and Optical Isomerism in Organic Chemistry
Advertisements

C.I. 3.6 Optical Isomerism.
High Level Organic Chemistry
Chemsheets AS006 (Electron arrangement)
Pharmaceutical ORGANIC CHEMISTRY.  Optical Isomerism  Polarimeter  Chirality  Chiral compounds  Enantiomers and diastereomers  Racemate.
Nitrogen Compounds Ammonia derivatives. Specification from OCR Properties of primary amines Properties of primary amines Amino acids; peptide formation.
Amines Ammonia derivatives. Specification from OCR o Explain the basicity of amines in terms of proton acceptance by the nitrogen lone pair. o Describe.
ISOMERS Learning Goals: I will understand the difference between structural isomers and stereoisomers (diastereomers and enantiomers) and be able to name/draw.
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.0 UK: England & Wales License Isomerism University of Lincoln presentation.
OPTICAL ISOMERISM. Occurrence another form of stereoisomerism occurs when compounds have non-superimposable mirror images Isomers the two different forms.
Welcome to class of Amino Acids Dr. Meera Kaur. Learning objectives To understand - the structural features of amino acids - the classifications of amino.
Amino acids are the building blocks of proteins. The general structure of amino acids includes an α-amino group, an α-carboxylate group and a variable.
Amino acids: Chemical and Physical Properties
Amino Acids ( 9/08/2009) 1. What are Amino Acids, and what is their 3-D structure? 2. What are the structures & properties of the individual amino acids?
Isomers Larry J Scheffler Lincoln High School IB Chemistry
Optical Isomerism.
Amino Acids and Proteins
CONTENTS Prior knowledge Structure and classification Nomenclature Physical properties Basic properties Nucleophilic properties Amino acids Peptides and.
Polypetides and proteins
Isomerism. Isomers are compounds that have the same molecular formula but have different arrangements of atoms in space. Isomers have different physical.
Optical isomerism L.O.:  Describe optical isomers as non-superimposable mirror images about an organic chiral centre.  Identify chiral centres in a molecule.
Amino Acids (Foundation Block) Dr. Sumbul Fatma Tel #
Amino acids. Essential Amino Acids 10 amino acids not synthesized by the body arg, his, ile, leu, lys, met, phe, thr, trp, val Must obtain from the diet.
II- Classification according to polarity of side chain (R): A- Polar amino acids: in which R contains polar hydrophilic group so can forms hydrogen bond.
Amino Acids, Isomerism and Condensation Polymers.
Chapter 11 – Carbon Chapter 11 Goals: 1.Classify organic compounds. 2.Recognize structural isomers and steroisomers. 3.Name and draw structures of common.
13.9 Amino Acids and Proteins. First things first… A BASIC AMINO ACID STRUCTURE Now lets split this amino acid into its 3 main component parts..
II- Classification according to polarity of side chain (R): A- Polar amino acids: Polar side chains contain groups that are either charged at physiological.
R W Grime Ripon Grammar School
Chapter 19: Proteins Spencer L. Seager Michael R. Slabaugh Jennifer P. Harris.
B- Classification according to polarity of side chain (R):
General method for synthesis of azo dyes Add a cold aqueous solution of sodium nitrite slowly (with cooling and stirring) to a cold solution of the amine.
Cissy Gao / Irene Meng / Zero Yao. Today’s Object Identify amino acids and understand their structure Identify the peptide bonds in dipeptides and polypeptides.
Amino acids structure, physical and chemical properties (Ch 2) Saida Almashharawi Basic Biochemistry CLS
AMIDES AND AMINO ACIDS AMIDES AND AMINO ACIDS. AMIDES Structurederivatives of carboxylic acids amide group is -CONH 2 NomenclatureWhite crystalline solids.
ERT 106 BIOCHEMISTRY Amino Acids Pn Syazni Zainul Kamal.
ISOMERISM.
OPTICAL ISOMERISM. All molecules have a mirror image – but for most molecules it is the same molecule.
Amino Acids, Peptides, and Proteins. Introduction to Amino Acids  There are about 26 amino acids, many others are also known from a variety of sources.
4.8 Amides 1. Amides 2 Amide functional group Amides Possible under high temp for extended time to prepare amide from a carboxylic acid and an amine.
PHARMACEUTICAL ORGANIC CHEMISTRY LEC 2. QI: Arrange the following sets in order of decreasing priority -H, -C 2 H 5, -CH 3, -C(CH 3 ) 3, -CH(CH 3 ) 2.
Stereoisomerism AH Chemistry Unit 3(c). Occurs due to the restricted rotation of C=C double bonds... two forms… CIS and TRANS STRUCTURAL ISOMERISM STEREOISOMERISM.
Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original State the general formula for an α-amino acid as RCH(NH 2 )COOH.
Nitrogen Compounds Ammonia derivatives.
OPTICAL ISOMERISM.
What do each of these have in common ? H 2 N C COOH H H.
단백질의 다양성 ( 그림 5.1) 5.1 아미노산 - 아미노산 이름 및 약어 ( 표 5.1), 표준아미노산 ( 그림 5.2), - 일반구조 ( 그림 5.3): α- 탄소원자, 곁사슬, 카르복실기, 아미노기 - 프로린은 고리모양 ( 곁사슬과 아미노질소사이 ) -pH7 에서.
HL only. Learning outcomes Understand: There are two sub-classes of stereoisomers - conformational isomers and configurational isomers Conformational.
Proteins. Chemical composition of the proteins. Properties of α- amino carboxylic acids.
Proteins. Chemical composition of the proteins
Starter A dye can be made from 4-methylphenylamine and 2,6-dimethylphenol, shown below 1)Identify the inorganic nitrogen-containing compound formed by.
Isomers Molecules with same molecular formula but their respective atoms are arranged differently in space 1.
Isomerism SCH4U Spring 2012.
Amino Acids (Foundation Block) 1 Lecture Dr. Usman Ghani
Stereoisomerism.
POLYMERISATION.
HL Physical Organic Chemistry: Supplementary Material
BIO201/BBT101 SPRING 2018 Introduction to Biochemistry & Biotechnology
ISOMERISM Mr. Sonaji V. Gayakwad Asst. professor Dept of chemistry
Learning Objectives (LO)
Isomers Molecules with same molecular formula but their respective atoms are arranged differently in space 1.
Proteins Describe what a protein is and give examples of what they are used for. Describe the structure and shape of the different types of proteins. Explain,
TYPES OF ISOMERISM STRUCTURAL ISOMERISM
Functional group isomerism
1.Structural 2.Stereo isomers - geometric - optical
Presentation transcript:

Amino Acids Organic compounds containing both the amine -NH 2 and carboxyl -COOH functional groups. Amine e.g. CH 3 CH 2 NH 2 ethylamine Carboxylic acid e.g. CH 3 COOH ethanoic acid. Simplest amino acid: aminoethanoic acid- glycine if you are a biologist.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original State the general formula for an α-amino acid as RCH(NH 2 )COOH. State that an amino acid exists as a zwitterion at a pH value called the isoelectric point. State that different R– groups in α-amino acids may result in different isoelectric points. Describe the acid–base properties of α-amino acids at different pH values.

Amino Acids Naturally occurring amino acids are all α amino acids. This means that both the carboxyl and the amino functional groups are on the SAME carbon atom. This leads to the general formula on the next slide. These compounds are BIFUNCTIONAL since both functional groups act independently of one another.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original General formula of an α-amino acid R means any organic side chain.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Structures of some amino acids

Physical Properties White solids With relatively high melting points glycine (the simplest) has a melting point of 235°C. Normally readily soluble in water Almost totally insoluble in non-polar solvents Soluble in both acids and bases (alkalis).

Reactions The carboxylic acid group is a proton donor: CO 2 H  COO - + H + The amine group is a proton acceptor (a base): -NH 2 + H +  –NH 3 + The amino acids tend to exist as ZWITTERIONS. These are formed when the carboxyl group and the amine group have undergone an internal acid-base reaction. A proton is transferred FROM the acid TO the amine group so that both ends are charged. The overall charge is zero because the positive and negative charges cancel each other out.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Formation of a zwitterion from glycine

Isoelectric Point pH value at which the amino acid exists as a zwitterion. Varies from amino acid to amino acid since the inductive effects of the side chains affects the acid and base strengths of different amino acids differently. The isoelectric point has an impact on the acid-base behaviour of the amino acids.

Amphoteric Behaviour Amphoteric means can react with both acid and base. pH below isoelectric point: The amino acid is a base and accepts a proton from the the acid. The amino acid is a positively charged ion. pH above isoelectric point: The amino acid is an acid and donates a proton to the base. The amino acid forms a negatively charged ion.

Leucine Isoelectric point pH Draw the displayed formula of leucine. 2. Show the structure of leucine at pH 5.98, 2.0 and 7.

Answers Nearly full displayed formula. Skeletal zwitterionic form at pH At pH7 behaves as an acid At pH2 behaves as a base H+H+ -

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Acid–base reactions of an amino acid

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Explain the formation of a peptide (amide) linkage between α-amino acids to form polypeptides and proteins. Describe the acid and alkaline hydrolysis of proteins and peptides to form α- amino acids or carboxylates.

Peptides and Polypeptides A peptide linkage is the –CONH- link This is formed in a CONDENSATION reaction between two amino acids with the loss of a water molecule. A peptide is a compound containing amino acids linked by peptide bonds. Dipeptide = 2 amino acids Tripeptide = 3 amino acids etc.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Formation of a dipeptide between glycine and alanine

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Alternative reaction of alanine and glycine

Peptides and Polypeptides A polypeptide is a long chain of amino acids joined by peptide links. A protein is a long polypeptide chain with more than 60 amino acid units. A polypeptide with 4 different amino acids.

Hydrolysis The breaking of a bond by reaction with water. Can be acid or base catalysed. Acid hydrolysis: Generally refluxed with aqueous (6mol dm -3 ) HCl for 24 hours. The product is the protonated form of the constituent amino acids. Alkaline hydrolysis Reflux with aqueous sodium hydroxide. Sodium salt formed.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Acid hydrolysis of a dipeptide

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Alkaline hydrolysis of a polypeptide chain

Isomerism Structural Isomers Stereo Isomers E/Z (cis- trans) Isomers Optical Isomers Stereo isomerism –same structural formula but different arrangements of groups in space.

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Describe optical isomers as non-superimposable mirror images about an organic chiral centre. Identify chiral centres in a molecule of given structural formula. Explain that optical isomerism and E/Z isomerism are types of stereoisomerism.

24 All molecules have a mirror image – but for most molecules it is the same molecule.

25 For some molecules the mirror image is a different molecule (the mirror image is non-superimposable). When this happens the 2 forms of the molecule are described as OPTICAL ISOMERS. Optical isomerism is a form of stereoisomerism.

Molecules that are optical isomers are called enantiomers. Enantiomers have identical chemical and physical properties, except: Their effect on plane polarised light; Their reaction with other chiral molecules. Many natural molecules are chiral and most natural reactions are affected by optical isomerism. In nature, only one optical isomer occurs (e.g. all natural amino acids are rotate polarised light to the left).

Light is a form of electromagnetic radiation.

The wave vibrations are perpendicular to the direction of travel of the wave.

Optical isomers rotate the plane of plane polarised light.

POsPNI&feature=relatedhttp:// POsPNI&feature=related

Left and right hands are an example of non- superimposable mirror images. Optical Isomerism

OPTICAL ISOMERISM Occurrence another form of stereoisomerism occurs when compounds have non-superimposable mirror images Isomers the two different forms are known as optical isomers or enantiomers they occur when molecules have a chiral centre a chiral centre contains an asymmetric carbon atom an asymmetric carbon has four different atoms (or groups) arranged tetrahedrally around it.

OPTICAL ISOMERISM Occurrence another form of stereoisomerism occurs when compounds have non-superimposable mirror images Isomers the two different forms are known as optical isomers or enantiomers they occur when molecules have a chiral centre a chiral centre contains an asymmetric carbon atom an asymmetric carbon has four different atoms (or groups) arranged tetrahedrally around it. There are four different colours arranged tetrahedrally about the carbon atom 2-chlorobutane exhibits optical isomerism because the second carbon atom has four different atoms/groups attached CHIRAL CENTRES

34 Most α amino acids are optically active – having non superimposable mirror image isomers. Exception?

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original The butan-2-ol molecule has a chiral carbon

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Optical isomers of CH 3 CH 2 CH(NH 2 )CH 3

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original Simplified three-dimensional representation of two optical isomers

TASK Which of the following molecules are optically active? 1)propan-2-ol 2)2-chlorobutane 3)1-chlorobutane 4)3-methylhexane 5)butanone 6)2-methylbutanoic acid 7)butan-2-ol 8)1-chloro-3-methylpentane

propan-2-ol NOT OPTICALLY ACTIVE

2-chlorobutane OPTICALLY ACTIVE

1-chlorobutane NOT OPTICALLY ACTIVE

3-methylhexane OPTICALLY ACTIVE

butanone NOT OPTICALLY ACTIVE

propan-2-ol NOT OPTICALLY ACTIVE

2-methylbutanoic acid OPTICALLY ACTIVE

butan-2-ol OPTICALLY ACTIVE

1-chloro-3-methylpentane OPTICALLY ACTIVE

S carvone (caraway seed)R carvone (spearmint) Caraway Seed has a warm, pungent, slightly bitter flavour with aniseed overtones.

S limonene (lemons)R limonene (oranges)

Week 7 © Pearson Education Ltd 2009 This document may have been altered from the original E and Z isomers of but-2-ene