Transcript Chlorophyll – Protein complex + H* _ OH – (Ground state)

KERANGKA TEORI
STRATEGI
MENINGKATKAN
RENDEMEN TEBU
bahan kajian
Diabstraksikan oleh
Prof Dr Ir Soemarno MS
PM PSLP PPSUB Agustus 2010
TEORI FOTOSINTESIS
Saccharum officinarum is particularily efficient in
producing an excess amount of sucrose. In fact This
process of taking in light energy and converting it
into other substances is called photosynthesis.
FOTOSINTESIS TEBU
TANAMAN C4
PENAMPANG DAUN TEBU
TANAMAN C4
PHOTO-IONIZATION
The excited chlorophyll-protein complex reacts with
water and splits the water into hydrogen ion (OH). This phenomenon is called photoionization.
Chlorophyll-protein complex (Excited) + H2O
------- Chlorophyll – Protein complex + H* _ OH
– (Ground state)
BIOSINTESIS KARBOHIDRAT
The CO 2 acceptor in C 4 plants is phosphoenolpyruvate
(PEP). PEP reacts with CO 2 to form oxaloacetic acid which is
reduced by NADPH to form malic acid. The malic acid then
reacts with RUBP to form pyruvic acid..
BIOSINTESIS GLUKOSE
TEORI KHLOROFIL
Photochemical Reaction Centre of the Light Harvesting
Antenna
When a chlorophyll molecule in the thylakoid membrane is
excited by light, the energy level of an electron in its
structure is boosted by an amount equivalent to the energy
of the absorbed light and the chlorophyll becomes excited.
The packet of excitation energy (The Exciton) now migrated
rapidly through the light harvesting pigment molecules to the
reaction centre of the photosystem where it causes an
electron to acquire the large amount of energy.
KHLOROFIL : PHOTOSYSTEM
Light, in the form of photons, excite the chlorophyll
molecules until it reaches the reaction center of Photosystem
II.
This allows an electron from one chlorophyll molecule to
jump to a higher energy level within the same chlorophyll
molecule.
MOLEKUL KLOROFIL INTI Mg
Chlorophyll is synthesized in chloroplasts from 8 molecules
of 5-aminolevulinic acid. The 8 red lines indicate the location
of the parts of 5-aminolevulinic acid in the finished
molecule. Position 3 that is a methyl group in chlorophyll a
(illustrated) is a formyl (CHO) group in chlorophyll b.
Molekul khlorofil
BIOSINTESIS KHLOROFIL
In higher plants 5-aminolevulinic acid is
synthesized from glutamic acid as illustrated in
Figure of von Wettstien et al. (1995):
BIOSINTESIS KHLOROFIL
A) An outline of the chlorophyll biosynthetic pathway. The
shaded area represents the region of the pathway under
control of ChlM.
B) The methyltransferase reaction catalysed by ChlM.
Abbreviations: ALA, d-aminolaevulinic acid; proto,
protoporphyrin IX; GGPP, geranyl-geranoyl
pyrophosphate; ChlM, magnesium protoporphyrin IX
methyltransferase; SAM, S-adenosyl-l-methionine; SAH,
S-adenosyl-l-homocysteine.
The biosynthetic pathway of chlorophyll and
heme.
BIOSINTESIS SUKROSE
BIOSINTESIS SUKROSE
Possible sites of sodum involvement in C4 photosynthesis:
stomatal conductance (A), carbonic anhydrase (B), activity of
PEP carboxylase (C) were all unaffected by sodium nutrition.
By contrast, leaves of sodium-deficient plants had high levels
of alanine and pyruvate and low levels of PEP in the
mesophyll chloroplasts (Original unpublished diagram
courtesy P.F. Brownell)
Pathway of starch synthesis in
chloroplasts
Carbon assimilated via the Calvin cycle is partitioned with a
fraction exported to the cytosol for sucrose synthesis and a
fraction retained in the chloroplast for starch synthesis.
Redox activation and allosteric regulation of AGPase
controls the flux of carbon into starch. Abbreviations: Fru6P,
fructose 6-phosphate; Glc1P, glucose 1-phosphate; Glc6P,
glucose 6-phosphate; TPT, triose-phosphate/phosphate
translocator.
The role of Fru-2,6-P2 in feedforward control of
sucrose synthesis.
Reactions shown are catalysed by the following enzymes:
1, Rubisco; 2, chloroplastic PGK and chloroplastic TPI; 3, chloroplastic
Fru-1-6-P2 aldolase; 4, chloroplastic FBPase; 5, transketolase,
sedoheptolase-1,7-bisphosphatase aldolase, sedoheptolase-1,7bisphosphatase, phosphopentoepimerase, phosphoriboisomerase and
phosphoribulokinase; 6, triose phosphate transporter; 7, cytoslic PGK
and cytosolic TPI; 8, cytosolic Fru-1-6-P2 aldolase; 9, cytosolic
FBPase; 10, cytosolic PGI ; 11, cytosolic PGM , 12, UGPase, 13, SPS,
14, sucrose phosphatase.
TRANSPORT SUKROSE
Pathways of sugar metabolism and compartmentation within
sink cells. Sugars can be delivered to sink cells through
either apoplasmic or symplasmic pathways.
Within the sink apoplasm, sucrose can be hydrolysed to
hexoses by an extracellular invertase.
TRANSPORT SUKROSE
In photosynthetic tissues sucrose is predominantly
exported from cells, most probably by facilitated
diffusion and subsequently taken up by the phloem
complex by a specific sucrose/H+ co transport
mechanism
Once in the phloem complex sucrose is transported to
cells in heterotrophic “sink“ tissues.
At least two distinct classes of sink tissues can be
differentiated:
(i) “utilisation sinks“, highly metabolically active, rapidly
growing tissues like meristems and immature leaves,
(ii) “storage sinks“, such as tubers, STEM, roots or fruits
which deposit imported carbohydrates as storage
compounds (e.g. starch, sucrose, lipid or protein).
Sucrose obtained through translocation, by sink tissues,
can enter a cell directly via the symplasm or the
apoplasm (whereby it is transported by specific
sucrose or, following cleavage to its component
hexoses, monosaccharide transporters.
Several studies using asymmetrically labelled sucrose
suggest that carbon obtained by heterotrophic cells
moves primarily through the symplastic route and is
not cleaved to glucose and fructose during transport.
Mobilisation of Sucrose in sink
tissues
Sucrose delivered to the sink tissue can be cleaved
in one of three ways:
(i)
in the apoplast, as described above, by the
action of an acid invertase or in the cytosol by
either
(ii) alkaline invertase or
(iii) sucrose synthase (SuSy).
The predominant route of sucrose unloading and
subsequent mobilization.
SUKROSE DALAM
JARINGAN SIMPANAN
The possible fates of sucrose unloaded apoplastically in sink
tissues.
(1) Sucrose that enters the apoplast can be split into glucose
and fructose by a wall invertase before entering a cell from a
sink tissue, or (2) sucrose can be taken up into the cell
unaltered. (3) Once in the symplast of the cell from the sink
tissue, sucrose can be split into glucose and fructose by a
cytoplasmic invertase, or (4) sucrose can enter the vacuole
unaltered. (5) Once in the vacuole, sucrose can be split into
glucose and fructose by a vacuolar invertase, or it can
remain unaltered.
METABOLISME SUKROSE
KATABOLISME SUKROSE
Sucrose is split by either invertase (β-fructofuranosidase) or
sucrose synthase .
Dashed arrows at the top differentiate alternative ‘starting
points’ for sucrose catabolism.
Products of sucrose breakdown contribute to a pool of
cytosolic glucose 6-P and fructose 6-P , which are freely
interconvertible in what is labelled ‘hexose-P pool’.
In the cytosol, fructose 6-P can be converted to fructose 1,6P2 by two different reactions, one catalysed by 6phosphofructokinase and the other by PPi–fructose-6-P 1phosphotransferase .
Dashed arrows indicate alternative sources of fructose 1,6P2. [PPi–fructose-6-P 1-phosphotransferase is confined to
cytosol , so if fructose 6-P is phosphorylated in plastids, only
one reaction is available.]
Fructose 1,6-P2 is converted to 2 phosphoenolpyruvate
(PEP) in glycolysis. As drawn, glycerone-P moves from
cytosol to plastid, although other glycolytic intermediates
(e.g. glucose 1-P, 3-P-glycerate and PEP) can also move from
cytosol to plastids .
The Pi exchanged for glycerone-P during cytosolic-plastidic
countertransport is balanced by net Pi releases in the plastid.
As drawn, the hexose-P pool supplies glucose 6-P to
plastids, where erythrose 4-P (E4P) is produced by cyclic
operation of the oxidative pentose phosphate pathway
(OPPP).
RESPIRASI
Respiration begin with breakdown of sucrose
to the hexose phosphates (hexose-P) glucose
6-P and fructose 6-P.
Sucrose breakdown is assumed to occur in
the cytosol, though it can also occur in the
apoplast.
Sucrose can be cleaved by invertase or
sucrose synthase .
The products of invertase action are glucose
plus fructose, which can be directly
phosphorylated to form glucose 6-P and
fructose 6-P, respectively.
Sucrose breakdown by sucrose synthase
yields fructose plus UDP-glucose.
This fructose can be phosphorylated directly,
giving fructose 6-P, and the UDP-glucose can
be converted to glucose 6-P in two steps.
STABILISASI UREA
Urea bersifat higroskopis dan mudah larut
dalam air
(Urea optimally hydrated: about 6 - 8 moles
water per mole urea )
Molekul Urea mengikat
Molekul Air
Molecular 'embrace' of an urea and a water
molecule
The water molecule is bonded to the urea
molecule by two water bonds (dotted lines).
The hydrogen atoms are indicated in white,
the oxygen atoms in red, the nitrogen atoms
in blue and the carbon atom in black .
NH2
CO
H2O
Molekul Urea higroskopis
dan mudah larut air
Solvation structure of the urea molecule from our
experiments.
One of the water molecules in the solvation shell
shares two hydrogen bonds with urea.
Geometri Kristal Urea
HIDROLISIS UREA
SECARA ENSIMATIS
UREASE: ENSIM HIDROLISIS UREA
Some microorganisms excrete an enzyme, Urease.
This highly effective enzyme rapidly hydrolyzes urea to
one molecule of Carbon Dioxide, and two molecules of
ammonia.
Because Carbon Dioxide is subject to evaporation, this
reaction rapidly increases environmental pH by the
production of Ammonium Hydroxide. Once in the
environment, Urease will hydrolyze urea to Ammonia
even though the excreting microbe is no longer alive.
If microbes have an abundance of energy-rich carbon
foods, and plenty oxygen, they will rapidly oxidize toxic
ammonia to harmless nitrates. These nitrates become
available for plant or microbe metabolism or if in excess,
decomposition to molecular Nitrogen.
On the other hand, if energy food to support microbe
growth is lacking, or if conditions go anaerobic, the
microbes are unable to detoxify ammonia by
transformation to nitrate.
When this sequence occurs, ammonia buildup can
quickly kill plants.
Biuret is formed by the controlled
decomposition of urea; condensing two
molecules of urea into a single molecule of
biuret, which retains three of the nitrogen
atoms.
Biuret is less soluble than urea.
ASAM HUMAT
Example of a typical humic acid, having a
variety of components including quinone,
phenol, catechol and sugar moieties
STRUKTUR ASAM HUMAT
The hypothetical structure for humic acid is shown
below.
It contains free and bound phenolic OH groups,
quinone structures, nitrogen and oxygen as bridge
units and carboxylic acid groups variously placed on
aromatic rings.
ASAM HUMAT MENGIKAT KATION
TERSEDIA
Because of the variable molecular composition of humic
acids, a wide range of dissociation constants exists for
the metals that are chelated by humic acids .
In addition, different metals are bound to humic acids with
varying strength, and this would mean that a particular
chelate-bond cation will modify the binding stability of the
other metal linkages.
This peculiar metal binding capacity of humic acids is
exemplified by the fact that when some alkali metals, such
as K and Na, are bound by previously empty functional
groups, then the chelated bonds of Fe and Al may rupture
easier than if the humic acid molecule contains an alkali
earth metal, such as Ca .
This peculiar metal binding capacity also protects plants
by the ability of water-soluble fractions of humic
substances (humic and fulvic acids) to form precipitates
with a number of metals (Ca, Cd, Hg, Pb, Ba), forming
insoluble complexes.
The complexes formed are not available to plants and the
concentration of toxications in the soil solution is reduced
.
KIMIAWI ASAM HUMAT
A typical humic substance is a mixture of many molecules,
some of which are based on a motif of aromatic nuclei with
phenolic and carboxylic subsituents, linked together; the
illustration shows a typical structure.
The functional groups that contribute most to surface
charge and reactivity of humic substances are phenolic and
carboxylic groups.
Humic acids behave as mixtures of dibasic acids, with a
pK1 value around 4 for protonation of carboxyl groups and
around 8 for protonation of phenolate groups.
There is considerable overall similarities among individual
humic acids. For this reason, measured pK values for a
given sample are average values relating to the constituent
species. The other important characteristic is charge
density.
The molecules may form a supramolecular structure held
together by non-covalent forces, such as Van der Waals
force, H-H, and CH-H bonds.
The presence of carboxylate and phenolate groups gives
the humic acids the ability to form complexes with ions
such as Mg2+, Ca2+, Fe2+ and Fe3+. many humic acids
have two or more of these groups arranged so as to enable
the formation of chelate complexes.
Pembentukan khelate merupakan aspek penting dari
peranan biologis dari asam humat dalam mengendalikan
ketersediaan hara logam.
Asam humat : Khelator
Asam humat mempunyai kemampuan
menjadi khelator.
A chelator is a molecule that binds metals,
including toxic heavy metals. It is able to
scavenge for these heavy metals and
eliminate them from the body.
It also seems to increase the permeability of
cell walls, allowing for easier transfer of
nutrient metals.
Research indicates that humic acid can bind
to essential metals as well; much like soil
humic acid did millions of years ago it can
provide nutrients to living things growing in
the soil.
Khelat Cu-asam humat
Bagan berikut menyajikan bagaimana kation Cu++
dikhelate oleh asam humat.
Kation Cu++ pada posisi sentral (pusat) dikhelat oleh
asam humat yang ukuran molekulnya lebih besar.
Kation ini diikat secara ionik oleh dua gugusan asam
karboksilat yang bermuatan negatif dan dikompleks
dengan satu gugus asam amino netral.
Secara bersama-sama ketiga gugusan ini mengikat kation
dengan kekuatan yang jauh lebih besar daripada kekuatan
masing-masing gugusan.
Skema pembentukan khelat logam M oleh
asam humat
MANFAAT ASAM HUMAT?
Mereduksi jumlah air yang diperlukan untuk
tanaman yang sehat.
Mereduksi penggunaan pupuk.
Mereduksi kebutuhan pestisida.
Helps control pollutant contamination.
Makes plants more drought, heat and cold
resistant.
Adds incredible diversity to the Soil Food Web.
Reduces the amount of water needed for healthy
plant.
Berfungsi sebagai bio-stimulant.
Memperbaiki sifat fisika tanah.
Menahan hara dalam bentuk dapat ditukar.
Memperbaiki kondisi lengas tanah.
Affects the release of plant nutrients through slow
decomposition.
Improves trace element nutrition through
chelation of metallic & non-metallic ions.
Chlorosis in plants has been prevented or
corrected by humate application.
ASAM HUMAT MEMPERBAIKI
STRUKTUR TANAH
ASAM HUMAT BLOCKER VIRUS
Humic acid's mechanism of action in these cases
is believed to be the blockage of a virus particle
from attaching to and entering a healthy cell.
Viruses can't replicate or divide without entering
and taking over the cell's DNA for the making of
more virus particles. By keeping one virus
particle from becoming thousands, it effectively
blocks the infection from happening.