INTRODUCTION OF MACROMOLECULE HISTORY OF MACROMOLECULE PROPERTIES TYPES OF MACROMOLECULE COMPLEX FORMATION  EXAMPLE- Chromatin Ribosome CONCLUSION REFERENCES

1. Organization of macromolecule complex
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

2. CONTENT
INTRODUCTION OF MACROMOLECULE
HISTORY OF MACROMOLECULE
PROPERTIES
TYPES OF MACROMOLECULE
COMPLEX FORMATION
EXAMPLE-
Chromatin
Ribosome
CONCLUSION
REFERENCES

3. INTRODUCTION
 A macromolecule is a very large molecule commonly created by
polymerization of smaller subunits.
 In biochemistry, the term is applied to the four conventional biopolymers
(nucleic acids, proteins, carbohydrates, and lipids), as well as non-polymeric
molecules with large molecular mass such as macrocycles .
 The individual constituent molecules of macromolecules are called
monomers (mono=single, meros=part).
 Small organic molecules are the basic stuff of life. Scientists call them
monomers. Mono means one.
 When monomers (small molecules) are joined together, they form larger
molecules called polymers.
 Poly means many. Think of the polymers as that brick wall. And when
polymers are joined together, they form “giant” molecules called
macromolecules. Macro means big.

4. HISTORY OF MACROMOLECULE
 The term macromolecule was coined by Nobel laureate Hermann Staudinger in
the 1920s, although his first relevant publication on this field only mentions
high molecular compounds (in excess of 1,000 atoms).
 At that time the phrase polymer, as introduced by Berzelius in 1833, had a
different meaning from that of today: it simply was another form of
isomerism for example with benzene and acetylene and had little to do with
size.

5. TYPES OF MACROMOLECULE
Macromolecules can be divided into 4 major categories :
 Proteins
 Carbohydrate
 Lipids
 Nucleic acid

6. COMPLEX FORMATION
 Hydrophobic interactions between membrane lipids and hydrophobic
domains of the protein.
 α helix type protein mostly found.
 Both the amino and carboxyl terminus contains many polar or charged
amino acids residue and are therefore hydrophilic.
 Segment in the center of protein contains hydrophobic, non polar amino
acid residues.
 Phospholipids molecules lie on the protein surface, their head groups
interacting with the polar amino acids residues at the inner and outer
membrane- water interfaces and their side chains associated with the non
polar residues. These annular lipids form a bilayer shell around the protein.

7.  Tyr and Trp residue – membrane interface anchors.
 Lys, His, Arg- positively charged – present on cytoplasmic membrane.
 Membrane proteins contain one or more covalently linked lipids – like long
chain fatty acid, isoprenoids, and sterols.
 Other interactions are ionic attraction between positively charged Lys residue in
the protein and negatively charged lipid head groups contribute the stability.
 Plasma membrane glycoproteins are always oriented with the oligosaccharide
bearing domain on the extracellular surface.

8. EXAMPLE-
 Chromatin
 Ribosome

9. Chromatin
Chromatin consists of DNA and Proteins
 The eukaryotic cell cycle produces remarkable changes in the structure of
chromosomes.
 In nondividing eukaryotic cells (in G0) and those in interphase (Gl, S, and G2), the
chromosomal material, chromatin, is amorphous and seems to be randomly
dispersed in certain parts of the nucleus.
 In the S phase of interphase the DNA in this amorphous state replicates, each
chromosome producing two sister chromosomes (called sister chromatids) that
remain associated with each other after replication is complete.
 Chromatin consists of fibers containing protein and DNA in approximately equal
proportions (by mass), along with a small amount of RNA.
 The DNA in the chromatin is very tightly associated with proteins called histones,
which package and order the DNA to structural units called nucleosomes.
 Also found in chromatin are many non histone proteins, some of which help
maintain chromosomes structure and others that regulate the expression of specific
genes.

10. Histones are small, basic protein
 Found in the chromatin of all eukaryotic
cells, histones have molecular weights
between 1 1 ,000 and 21,000 and are
very rich in the basic amino acids
arginine and lysine (together these make
up about one-fourth of the amino acid
residues).
 All eukaryotic cells have five major
classes of histones, differing in molecular
weight and amino acid composition.
 Such modifications affect the net electric
charge, shape, and other properties of
histones, as well as the structural and
functional properties of the chromatin,
and they play a role in the regulation of
transcription.

11. Nucleosome are fundamental
organizational units of chromatin
 The eukaryotic chromosome depicted in represents the compaction of a DNA molecule
about 105 pm long into a cell nucleus that is typically 5 to 10 pm in diameter.
 This compaction involves several levels of highly organized folding.
 Subjection of chromosomes to treatments that partially refold them reveals a structure
in which the DNA is bound tightly to beads of protein, often regularly spaced.
 The beads in this "beads-on-a-string" arrangement are complexes of histones and DNA.
 The bead plus the correcting DNA that leads to the next bead form the nucleosome the
fundamental unit of organization on which the higher-order packing of chromatin is
built.
 The bead of each nucleosome contains eight histone molecules: two copies each of H2A,
H2B, H 3, and H4.
 The spacing of the nucleosome beads provides a repeating unit typically of about 200 bp,
of which 146 bp are bound tightly around the eight-part histone core and the remainder
serve as linker DNA between nucleosome beads.

12. Types and properties of histone
Histone
H1.
H2A
H2B
H3
H4
Molecular
weight
21,130
13,960
13,774
15,273
11,236
Number of
amino acid
residues
223
129
125
135
102
Content of basic
amino
acids (% of total)
Lys Arg
29.5 11.3
10.9 19.3
16.0 16.4
19.6 13.3
10.8 13.7

13. Nucleosome are Packed into successively
Higher-0rder structures
 Wrapping of DNA around a nucleosome core compacts the DNA length about
sevenfold. The overall compaction in a chromosome however, is greater than
10,000-fold-ample evidence for even higher orders of structural organization.
 In chromosomes isolated by very gentle methods, nucleosome cores seem to be
organized into a structure called the 30 nm fiber.
 Organization in to 30 nm fibers does not extend over the entire chromosome but
is punctuated by regions bound by sequence- specific (non histone) DNA-binding
proteins.
 The 30 nm structure also seems to depend on the transcriptional activity of the
particular region of DNA.
 The presence of topoisomerase II further emphasizes the relationship between
DNA under winding and chromatin structure.

15. The Ribosome complex supramolecular
Machine
 Bacterial ribosomes contain about 65%of rR NA and 35% of protein; they have a diameter of
about 18 nm and are composed of two unequal subunits with sedimentation coefficients of 30S
and 50S and a combined sedimentation coefficient of 70S.
 Both subunits contain dozens of ribosomal proteins and at least one large rRNA .
 Followug Zamecnik's discovery that ribosomes are the complexes responsible for protein
synthesis and following elucidation of the genetic code, the study of ribosomes
accelerated.
 I n the late 1960sMasayasu Nomura and colleagues demonstrated that both ribosomal
subunit can be broken down into their RNA and protein components, then reconstituted
in vitro.
 Under appropriate experimental conditions, the RNA and protein spontaneously reassemble to
form 30S or 50S subunits nearly identical in structure and activity to native subunits.
 First, the traditional focus on the protein components of ribosomes as shifted.
 The ribosomal subunits are huge RNA molecules. In the 50S subunit, the 55 and 23S rRNAs form
the structural core.
 The proteins are secondary elements in the complex, decorating the surface. Second and most
important, there is no protein within 18 A of the active site for peptide bond formation.

17.  The ribosomes of eukaryotic cells( other
than mitochondrial and chloroplast
ribosomes) are larger and more complex
than bacterial ribosomes (Fig. 27-15),
with a diameter of about 23 nm and a
sedimentation coefflcient of about 80S.
 They also have two subunits, which vary
in size among species but on average are
60S and 40S. A together, eukaryotic
ribosomes contain more than 80 different
proteins.
 The ribosomes of mitochondria and
chloroplasts are somewhat smaller and
simpler than bacterial ribosomes
nevertheless ribosomal structure and
function are strikingly similar in all
organisms and organelles.


18. Conclusion
 Macromolecular complexes are naturally
occurring machines inside cells. They consist of a
handful to several thousand individual
components, including proteins, DNA,
carbohydrates and lipids, and perform diverse
and vital tasks, such as translating the genetic
code, converting energy or helping nerve cells
communicate.

19. References
 BOOK- Lehninger Principle of Biochemistry – 5th
edition – David L. Nelson and Michael M. Cox.
 INTERNET- http://en.wikipedia.org