Thursday, December 3, 2009
Ionophores are Organic molecules of diverse types, many of which are antibodies of bacteria origin. Cells and organelle actively maintain concentration gradients of various ions across their membranes (e.g., Na+, K+ - pump). The antibiotic properties of ionophores arise from their tendency to discharge these concentration gradient.
Tuesday, December 1, 2009
Ceruloplasmin is a glycoprotein. The copper atoms are an integral point of Ceruloplasmin structure. There are 7-8 copper atoms per molecule. One half of the copper in crystalline Ceruloplasmin is in Cu2+ state. All these Cu2+ ions are not equivalent. The other half of copper remain in the Cu+ state.
The Cu2+ ions of Ceruloplasmin are reduced by Fe2+ and oxidised by molecular O2 in a cyclic process, called Ferroxidase activity. Ceruloplasmin oxidise (+ve state of ) Fe2+ to Fe3+, which then bind to transferrin.
Patent's suffering from wilson's disease may exhibit masked deficiency of Ceruloplasmin. This copper deficiency inhibits haemoglobin bio synthesis and ultimately leads to death.
Monday, November 30, 2009
Supra-molecular chemistry involves self-assembly or spontaneous association of several (2 or more) molecular components into a discrete non-covalently bound aggregate with a well defined structure. When highly complex structures are obtained from such units, the process is sometimes called self-organization.
Self assembly involves molecular recognition processes (binding events). Molecular recognition relies upon complementary of size, shape and chemical functionalities.
The partners of supra-molecular species have been named molecular receptor and substrate. The substrate usually being the smaller component whose binding is being sought. It is also sometimes called host-guest interaction. The binding of a substrate S to a receptor R yields the supra-molecule RS and involves a molecular recognition process. In order to achieve high recognition it is desirable that the receptor and substrate be in contact over a large area. This occur when the receptor is able to wrap around its guest so as to establish numerous non-covalent binding interactions and to sense its molecular size, shape and architecture.
In addition to binding sites, the receptor also carries reactive functions, it may effect chemical transformation on the bound substrate, thus behaving as a supra-molecular catalyst.
A lipophilic membrane soluble receptor may act as a carrier effecting the translocation of the bound substrates across the membrane. Thus, molecular recognition, transformation and translocation represent some of the basic functions of supra-molecular species. Supra-molecular chemistry has thus contributed in the construction of receptors, transfer agents enzyme models and extended arrays.
The concepts of the molecular recognition and complementarity are common in biological systems. complementarity between H-bonding groups on the twin strands of DNA is what makes the double helix stable. Molecular recognition is also part of the so called 'lock and Key' mechanism of enzyme action and transport of ions across membranes.
Supra-molecular chemistry first synthetic receptors were able to recognize the simplest of the substrates, the alkali metal ions. Receptors that recognize these ions already exist in nature. An example is the ionophore valinomycin which is a cyclic peptide molecule that binds specifically K+ ions and transports them across cell membranes. Valinomycin's ability to recognize and bind K+ ions selectivity is due to its geometrical complementarity, the cavity being of the rigid size to bind K+ ions. Na+ ions are smaller and are not bound by valinomycin. In addition to geometrical complementarity, valinomycin is a good receptor because of the presence of several interaction sites (Carbonyl groups) so that strong binding is possible.
It was the search of the synthetic analogues of natural ionophores that led to the discovery of cyclic ethers or crown ethers as receptors for metal ions (pederson). Crown ethers contain oxygen atoms in a cyclic structure with a central cavity with right size to fit the target ion. e.g., 18-crown-6 and 15-crown-5
In 18-crown-6 a cavity of the right size to fit K+ ions. It can, therefore, recognise and selectively bind to K+.
Subsequently, bicyclic molecules were synthesized in which nitrogen atoms unite three ether chains. These receptor molecules are three dimensional receptors with roughly spherical cavities, that bind alkali metal ions more tightly than do the single ring crown ethers. These molecules were called Cryptands and their metal complexes Cryptates. The metal ion binding ability of cryptands is selective, i.e, they exhibit molecular recognition. The selectivity is dependent on the size of the cavity.
Tricyclic receptors have also been developed which could bind large cations such as Cs+ and also NH4+ ions in their cavity.
In all these systems, the preference for a particular metal ion depends on a subtle balance between several thermodynamic factors.
a) binding energy (enthalpy)
b) gain or loss of configurational freedom (entropy) when the solvent cage of the metal ion is replaced by the ether cage.
This is characteristic of all supra-molecular complexes.
The Crown ethers and Cryptands highlighted the features that help good molecular recognition of a substrate by a receptor and helped in the construction of new receptors. They showed forinstance, how increasingly strong selective binding results from an increasing degree of pre-organization of binding groups in the receptor.
Receptor molecule with rigid cavities have the advantage that the binding sites are already in place before a substrate is bound. The binding sites donot have to organize themselves during the process of binding. In other words, they have a high degree of pre-organization and hence exhibit good molecular recognition properties such receptor molecules with relatively rigid cavities are known in nature of particular interest is the class of naturally occurring carbohydrates called Cyclodextrins, alpha-, beta-, and gamma- which contains 6, 7 and 8 glucose units respectively, linked head to tail in a ring. These molecules have a cylindrical cavity running through their centre in which small molecules can fit. The outer face of a cyclodextrin is hydrophilic with hydroxyl groups that have H-bonding ability so that the molecule is soluble in water. The inner cavity is lined mainly with C-C and C-H groups and is hydrophobic. Hence the cavity is able to receive and bind hydrophobic molecules such as benzene and phenylmethyl ether. Such receptor-substrate complexes are also called host-guest complexes or inclusion complexes. The molecular recognition in them is governed by complementarity of size and affinity (hydrophobicity) between cyclodextrin cavity and the molecule. Cyclodextrins have been investigated as enzymes mimics that enhance the selectivity of a chemical transformation carried out on the bound substrate. It was found that the H-atoms of the benzene ring of phenyl methyl ether could be substitued by chlorine specifically in the para position when the molecule was bound with a cyclodextrin. Only the para-hydrogen protruding from the bottom of the cavity was exposed to chlorine attack.
Synthetic rigid cavity receptors are also known. For example, formaldehyde and phenol derivatives can form cyclic oligomers which adopt a cup-like shape and are called calixarenes. Synthetic methods of making a wide range of calixarenes with different numbers of phenolic groups in the calix(n)arenes, where n denotes the number of phenol groups in the ring. For e.x., calix(4)arene has four phenol groups in the ring. The lining of benzene rings in the bowl shaped cavities of calixarenes allows them to acts as 'molecular baskets' for hydrophobic substrate like toluene, benzene and xylene.
The strength with which the substrate is bound depends on the complementarity of size. For e.x., toluene is firmly embedded in the bowl of a calix(4)arene but it is only loosely bound in the large cavity of calix(8)arene. It has been found that calix(7)arene will exhibit molecular recognition towards carbon cage fullerene molecules C60 and C70. The former with a soccer ball shape is bound tightly in the cavity, whereas the latter, with a rugby ball shape, is not. This provides a means of separating the two molecules which are generally formed in an intimate mixture.
Metal ions can serve as templates, that guide ligands into a particular arrangement. They, there by, act as organizing centers for synthesis of large supra-molecular assemblies from many component parts. In other words metal templation offers an effective approach to the self assembly of recognition sites.
Metal ions that form 4 coordinate square complexes are well suited to act as 90degree corners of square supra-molecular structures.
Metal ions with tetrahedral coordination geometries have been used as organizing centers for the multistep assembly of double helices (helicates). The two ligands twist around several metal ions in a double helical fashion. The two strands in these contain metal bound bipyridine units linked together. The efficiency of the self assembly process is the result of positive co-operativity, whereby the binding of one metal ion pre-organizes the ligands to facilitate the binding of the second. In other words, the assembly process gets easier as it progresses.
Similar strategies have been used to obtain molecular assemblies described as catenanes and rotaxanes. An assembly in which one ring is linked through another is called a catenane. A rotaxane is a linear molecule threaded through a cyclic molecule. Unthreading is prevented by subsequently adding bulky end caps.
One of the goals of supra-molecular chemistry is to build synthetic systems that carry out some of the functions of biochemical systems - trans membrane ion transport, enzyme -like catalysis, conducts for channeling electrons and chemical sensors with high sensitivity and selectivity.
Sunday, November 29, 2009
Hi friends here is the story of Ant, representing the today's work culture in an Organization. I found in the net thinking you too like it....
Every day, a small ANT arrives at work very early and start work very immediately. She produces a lot and she was happy.
The Chief, a LI ON was surprised to see that the Ant was working without supervision. He thought if the Ant can produce without supervision, wouldn't she produce even more if she had a supervisor!
So he recruited a COCKROACH who had an extensive experience as supervisor and who was famous for writing excellent reports. The Cockroach's first decision was to set up a clocking in attendance system. He also needed a secretary to help him write and type his reports.
He recruited a SPIDER, who managed the archives and monitored all phone calls.
The lion was delighted with Cockroach's report and asked him to produce graphs to describe production rates and analyze trends, so that he could use them for presentations at Board meetings.
So the Cockroach has to buy new computer and laser printer and recruited a FLY to manage the IT department.
The Ant, who had once been so productive and relaxed, hated this new plethora of paper work and meetings which used up most of her time.
The lion to the conclusion that it was high time to nominate a person in charge of department where the Ant worked.
The position was given to CICADA, whose first decision is to buy a carpet and an ergonomic chair for his office. The new person in charge, the Cicada, also needed a computer and personal assistant, who he brought from his previous department, to help him work and Budget control strategic optimization plan.
The department where the Ant works is the sad place, where nobody laughs anymore and everybody become upset.
It was at that time the Cicada convinced the Boss, the lion, of the absolute necessity to start a climatic study of the environment. Having reviewed the charges for running the Ant's department, the lion found out that the production was much less than before.
You are Right, the lion fires as per your GUESS !
Saturday, November 28, 2009
Friday, November 27, 2009
Fast moving consumer goods (FMCG), also known as consumer packaged goods (CPG) are the products that have a quick turnover and relatively low cost. Consumers generally put less thought into the purchase of FMCG than they do for any other products.
The Indian FMCG industry witnessed significant changes through through 1990's. Many players had been facing severe problems on account of increased competition from small and regional players and from slow growth across its various product categories. As a result, most of the companies were forced to revamp their product, marketing, distribution and customer service strategies to strengthen their position in the market.
By the turn of 20th century, the face of Indian FMCG industry had changed significantly. With the liberalization and growth of economy, the Indian customer witnessed an increasing exposure to new domestic and foreign products through different media, such as television and the Internet. Apart from this, social changes such as an increase in the number of nuclear families and the growing number of working couples resulting in increased spending power also contributed to the increase in the Indian consumer's Personal consumption. The realization of the customer's growing awareness and the need to meet changing requirements and preferences on account of changing lifestyles required the FMCG producing companies to formulate customer-centric strategies. These changes have a positive impact, leading to the rapid growth in the FMCG industry. Increased availability of retail space, rapid urbanization and qualified manpower also boosted the growth of the organized retailing sector.
HUL led the way in revolutionizing the product, market, distribution and service formats of the FMCG industry by focusing on rural markets, direct distribution, creating new product, distribution and service formats. The FMCG sector also received a boost by the government led initiatives in the 2003 budget such as setting up of excise free zones in various parts of the country that witnessed firms moving away from outsourcing to manufacturing by investing in the zones.
Though the absolute profit made on FMCG products is relatively small, they generally sell in large numbers and so the cumulative profit on such products can be large. Unlike some industries, such as automobiles, computers and airlines FMCG doesn't suffer from mass layoffs ever time the economy starts to dip. A person may put off buying a car but he Will not put off having his dinner.
Unlike other economy sectors, FMCG share float in a steady manner irrespective of global market dip, because they generally satisfy rather fundamental, as opposed to luxurious needs. The FMCG sector which is growing at a rate of 9% is the fourth largest sector in the Indian economy and is a worth of Rs. 93000 crores. The main contributor, making up 32% of the sector, is the south Indian region. It is predicted that in the year 2010, the FMCG sector will be worth Rs.143000 crores. The sector being one of the biggest sectors of the Indian economy provides upto 4 million jobs.
The FMCG sector consists of the following categories:
Personal care - Oral care, Hair care, Wash (soaps), Cosmetics and Toiletries, Deodorants and perfumes, Paper products (Tissues, Diapers, Sanitary products) and Shoe care; the major players being Hindustan Uni-liver Limited, Godrej Soaps, Colgate, Marico, Dabur and Procter & Gamble.
Household Care - Fabric wash (laundry soaps and detergents), Household cleaners (Dish/utensil/floor/toilet cleaners), Air fresheners, Inseticides and Mosquito repallants, Metal polish and Furniture polish; the major players being Hinduatn Uni-liver Limited, Nirma and Ricket Colman.
Branded and Packaged Foods and Beverages - Health beverages, Soft drinks, Staples/Cereals, Bakery products (Biscuits, Breads, cakes), Snack foods, Chocolates, Ice-creams, Tea, Coffee, Processed fruits, Processed vegetables, Processed Meat, Branded flour, Bottled water, Branded rice, Branded sugar, Juices; the major players being Hindustan Uni-liver Limited, Nestle, Coca-Cola, Cadbury, Pepsi and Dabur.
Spirits and Tobacco - The major players being ITC, Godfrey, Philips and UB.
Thursday, November 26, 2009
NO is a vital and the first gaseous biological messenger to be identified. It diffuses freely across membranes, but has a short life less than a few seconds, because it is highly reactive. Hence, NO is well suited to serve as a transient signal molecule within cells and between adjacent cells.
Nitric Oxide is produced in the brain and serves as a neuro transmitter. It causes muscle cells to dilute and relax. It acts as a mediator of blood vessel relaxation and thus brings down blood pressure. This function is partly brought about by the activation of guanyl cyclase. Its formation is regarded as the main determinant of blood pressure in many species, including man.
Nitric oxide also participates in the transmission of nerve impulses, which is important in a range of activities, including gut contraction and food movement as well as penile erection.
NO is an effective killer of cells (Cytotoxic) or blocker of cell multiplication and growth (Cytostatic). It's known antibacterial activity possibly occurs via the generation of other radicals.
There are three variety of inhibitor of NO3 action and there may be of value in the treatment of certain clinical conditions arising from irregular production of NO.