A. Denaturation
Denaturation
of proteins may imply a change or modification of the secondary
structure, tertiary and quaternary protein molecule without breaking
the covalent bonds. Therefore,
a process of denaturation can be interpreted breaking hydrogen bonds,
hydrophobic interactions, and salt bonds open pleat folds or protein
molecules (Sumardjo, 2008).Results denaturation is the loss of biochemical activity of a protein that occurs in the compound itself. Denaturation of the protein did not affect the primary structure of the protein content of the C, H, O, and N. Although some proteins undergo containing compounds likely to lose their structural characteristics as denaturation. However,
most proteins will not experience it, it's just that it is possible to
change the structure of protein is also little inside when denaturation
process occurs. However, for the denaturation changes in general, the process is the same and can not be changed. (Stoker, 2010)The factors that cause the denaturation of the protein, among others:1. Temperature in the environment2. pH3. pressure4. electricity5. a mixture of chemicals6. alcohol7. reducing agentsDenaturation
process progress steadily, and does not change, a protein that undergo
denaturation process will change the solubility of liquid viscosity or
reduced so easily settled. Chemical
compounds such as urea and salt can break the hydrogen bonds cause
protein denaturation because it can break hydrophobic interactions and
increase the solubility of hydrophobic groups in water. Detergent
or soap can cause denaturation due to compounds in detergents can form
a bridge between hydrophobic to hydrophilic groups resulting in
denaturation. In addition to detergents and soaps, acetone and alcohol can also cause denaturation (Winarno, 2008).
B. MECHANISM denaturation
a. Denaturation due to heavy metalHeavy metal salts with protein denaturation as acids and bases. Heavy metal salts generally contain Hg +2, Pb +2, Ag +1 Tl +1, Cd +2 and other metals with large atomic weight. The reaction that occurs between heavy metal salts will result in the formation of protein-metal salts are not soluble (Ophart, CE, 2003). Protein will experience precipitation when reacted with metal ions. Deposition by positive ions (metal) solution of the above required ph pi because negatively charged protein, deposition by negative ion required under pi ph solution as positively charged protein. Positive ions that can precipitate the proteins are: Ag +, Ca + +, Zn + +, Hg + +, Fe + +, Cu + + and Pb + +, while negative ions which can precipitate the protein is; ion salicylate, triklorasetat, piktrat, tanat and sulfosalisilat.b. Denaturation due to heatHeat can be used to disrupt hydrogen bonds and hydrophobic interactions of non-polar. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Proteins undergo denaturation and coagulated egg during cooking. Some of the food is cooked for protein denaturation was conceived to facilitate the digestive enzymes to digest the protein. Warming will make denatured protein material that decreases its water binding capabilities. This occurs because the thermal energy will result in disconnection of non-covalent interactions that exist in the natural structure of the protein but does not break the bonds that form covalent peptide bonds. This process usually takes place in a narrow temperature range.c. Due to acid and alkaline denaturationProtein will experience the greatest turbidity reached at ph ph isoelektris ie where the protein has a positive and negative charges are equal, when proteins undergo denaturation is marked turbidity increased and the incidence of clots. (Anna, P., 1994). Acids and bases can disrupt the salt bridges with the ionic charge. A type of double replacement reaction occurs when positive and negative ions in the salt change partners with positive and negative ions derived from acid or base added. This reaction occurs in the digestive system, stomach acid when consumed milk mengkoagulasi.d. Denatursi due to alcoholAlcohol can also protein denaturation. Alcohol, as we know there is a general level of 70% and 95%. 70% alcohol can enter the cell wall and protein denaturation in the cell. Whereas 95% alcohol mengkoagulasikan protein outside the cell wall and prevents other alcohol into the cell through the cell wall. So it is used as a disinfectant is 70% alcohol. Alcohol denaturation of proteins with intramolecular hydrogen bonds break at the protein side chains. The new hydrogen bonds can be formed between the alcohol and the protein side chains.e. Disulfide bond reducing agents damageDisulfide bonds formed by the oxidation of sulfhydryl groups on cysteine. Between different protein chains that have the same sulfhydryl groups to form a covalent disulfide bond is very strong. Reducing agents can decide disulfide bonds, where the addition of a hydrogen atom to form a thiol group;-SH. (Williams, 1950)
C. EFFECTS ON THE PRODUCT THAT IS DUE denaturation
1. Denaturation by heat conducted on fruit will result in reduced water content and increasing viscosity or viscosity levels of the protein embedded in the fruit are experiencing due to heat denaturation.2. Other impacts due to denaturation process is for example in meat products, the pH changes caused partially denatured proteins and changes in protein content. Changes in protein content will change the distance between the fibers of the meat so that it affects the ability to absorb and reflect light which will affect the appearance (color) of meat visually (Chayati, 2009).
D. Protein denaturation EXAMPLE OF DAILY LIFE
B. MECHANISM denaturation
a. Denaturation due to heavy metalHeavy metal salts with protein denaturation as acids and bases. Heavy metal salts generally contain Hg +2, Pb +2, Ag +1 Tl +1, Cd +2 and other metals with large atomic weight. The reaction that occurs between heavy metal salts will result in the formation of protein-metal salts are not soluble (Ophart, CE, 2003). Protein will experience precipitation when reacted with metal ions. Deposition by positive ions (metal) solution of the above required ph pi because negatively charged protein, deposition by negative ion required under pi ph solution as positively charged protein. Positive ions that can precipitate the proteins are: Ag +, Ca + +, Zn + +, Hg + +, Fe + +, Cu + + and Pb + +, while negative ions which can precipitate the protein is; ion salicylate, triklorasetat, piktrat, tanat and sulfosalisilat.b. Denaturation due to heatHeat can be used to disrupt hydrogen bonds and hydrophobic interactions of non-polar. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Proteins undergo denaturation and coagulated egg during cooking. Some of the food is cooked for protein denaturation was conceived to facilitate the digestive enzymes to digest the protein. Warming will make denatured protein material that decreases its water binding capabilities. This occurs because the thermal energy will result in disconnection of non-covalent interactions that exist in the natural structure of the protein but does not break the bonds that form covalent peptide bonds. This process usually takes place in a narrow temperature range.c. Due to acid and alkaline denaturationProtein will experience the greatest turbidity reached at ph ph isoelektris ie where the protein has a positive and negative charges are equal, when proteins undergo denaturation is marked turbidity increased and the incidence of clots. (Anna, P., 1994). Acids and bases can disrupt the salt bridges with the ionic charge. A type of double replacement reaction occurs when positive and negative ions in the salt change partners with positive and negative ions derived from acid or base added. This reaction occurs in the digestive system, stomach acid when consumed milk mengkoagulasi.d. Denatursi due to alcoholAlcohol can also protein denaturation. Alcohol, as we know there is a general level of 70% and 95%. 70% alcohol can enter the cell wall and protein denaturation in the cell. Whereas 95% alcohol mengkoagulasikan protein outside the cell wall and prevents other alcohol into the cell through the cell wall. So it is used as a disinfectant is 70% alcohol. Alcohol denaturation of proteins with intramolecular hydrogen bonds break at the protein side chains. The new hydrogen bonds can be formed between the alcohol and the protein side chains.e. Disulfide bond reducing agents damageDisulfide bonds formed by the oxidation of sulfhydryl groups on cysteine. Between different protein chains that have the same sulfhydryl groups to form a covalent disulfide bond is very strong. Reducing agents can decide disulfide bonds, where the addition of a hydrogen atom to form a thiol group;-SH. (Williams, 1950)
C. EFFECTS ON THE PRODUCT THAT IS DUE denaturation
1. Denaturation by heat conducted on fruit will result in reduced water content and increasing viscosity or viscosity levels of the protein embedded in the fruit are experiencing due to heat denaturation.2. Other impacts due to denaturation process is for example in meat products, the pH changes caused partially denatured proteins and changes in protein content. Changes in protein content will change the distance between the fibers of the meat so that it affects the ability to absorb and reflect light which will affect the appearance (color) of meat visually (Chayati, 2009).
D. Protein denaturation EXAMPLE OF DAILY LIFE
1. Denaturation of the protein in milkMilk protein consists of two main proteins: casein (~ 80%) and whey protein. Casein is very stable on heating, while whey protein is unstable in the presence of heat. Therefore, whey protein is denatured when milk was heated during pasteurization. Whey protein coagulated by heat and form tiny particles. Because the number of small particles is very small, infrequent precipitation.Whey protein denaturation events affecting white susu.Susu be whiter after pasteurized. Increase in milk white color is due to a change in refractive index caused by the denaturation of whey proteins.When milk is heated, the water evaporates on the surface of the milk causes the milk protein deposition irreversible. It is also caused by milk fat deposition attached to the protein. This membrane appears to consist of 70% fat and 20-25% protein (mainly lactalbumin from whey protein). Membrane
is rich in flavor and nutritional content because it contains fat and
protein.Susu sometimes coagulates by heat and acid. In both these cases, the clots caused by the denaturation of milk proteins.
2. Denaturation of the protein in meatHeating process may result in denaturation of the protein in meat that cause changes in the structure of the meat becomes dry, the moisture content is reduced, and become chewy.Heating can cause the meat to be tough protein fibers by coagulation and shrinkage due to myofibrillar and connective tissue proteins. Fast cooking process will make the meat tough as warming occurs during protein denaturation and denaturation of collagen, which is followed by shrinkage and tension in the connective tissue, so that the meat becomes tough. Peliatan occurs when proteins undergo denaturation at 50-800C.Perubahan this structure depends on the heating time, temperature, and the amount of collagen that is in the flesh. The cooking process is long enough to reach temperatures that exceed the collagen shrinkage temperature (60-650C), will make the meat becomes tender because collagen is converted into gelatin. Pengempu process or hydrolyzed collagen into gelatin occurs when cooking temperatures reach more than 750C.The heat is used to disrupt hydrogen bonds and hydrophobic interactions of non-polar. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Warming will make denatured protein material that decreases its water binding capabilities. This occurs because the thermal energy will result in disconnection of non-covalent interactions that exist in the natural structure of the protein but does not break the bonds that form covalent peptide bonds. This process usually takes place in a narrow temperature range.3. Denaturation of the protein in eggsHeating the egg whites at a temperature of about 60 C-70 C resulted albumin unfold and produce a precipitate is a solid white. This sediment can not return to its original shape. Similarly, the enzyme is heated at high temperatures. The enzyme is inactive and can not work anymore as biocatalyst.4. Denaturation of the protein in the hairProtein in human hair consists of elements of cystine, which is a compound that has an element asamamino sulfide, in a fairly high percentage of the amount. Disulfide bridge of cystine-SS-is one of the main factors responsible for the various forms yangbertanggung of our hair. Straight or curly hair because the keratin molecule containing bridges disulfidayang make mampuuntuk maintain certain forms.Rebonding process involves a chemical process that changes the structure of the protein in the hair. Rebonding process produces permanent changes in the affected hair applications. But the new hair that grows from the root hair rambutakan still have the original form. So, instead of straightening hair rebonding using only ordinary physical treatment, but also using chemical treatments that alter the structure of the protein in the hair permanently. Rebonding process through a process that uses heat pencatokan. Heating resulted in breaking the bonds making up proteins, such as hydrogen bonds break.5. Use of AntibioticsProteins present in the form of three-dimensional folds, which are determined by covalent intramolecular disulfide bonds and a number of noncovalent bonds such as ionic bonding, hydrophobic, and hydrogen. This form is called the tertiary structure of the protein, which is easily disturbed by a number of chemical or physical agent, causing the protein to be not working. Examples of antibiotics which will cause denaturation of proteins, namely: Group tetracyclines, macrolides Group.
E. REFERENCES
2. Denaturation of the protein in meatHeating process may result in denaturation of the protein in meat that cause changes in the structure of the meat becomes dry, the moisture content is reduced, and become chewy.Heating can cause the meat to be tough protein fibers by coagulation and shrinkage due to myofibrillar and connective tissue proteins. Fast cooking process will make the meat tough as warming occurs during protein denaturation and denaturation of collagen, which is followed by shrinkage and tension in the connective tissue, so that the meat becomes tough. Peliatan occurs when proteins undergo denaturation at 50-800C.Perubahan this structure depends on the heating time, temperature, and the amount of collagen that is in the flesh. The cooking process is long enough to reach temperatures that exceed the collagen shrinkage temperature (60-650C), will make the meat becomes tender because collagen is converted into gelatin. Pengempu process or hydrolyzed collagen into gelatin occurs when cooking temperatures reach more than 750C.The heat is used to disrupt hydrogen bonds and hydrophobic interactions of non-polar. This occurs because high temperatures can increase the kinetic energy and cause the building blocks of protein molecules move or vibrate so fast that disrupt the molecular bonds. Warming will make denatured protein material that decreases its water binding capabilities. This occurs because the thermal energy will result in disconnection of non-covalent interactions that exist in the natural structure of the protein but does not break the bonds that form covalent peptide bonds. This process usually takes place in a narrow temperature range.3. Denaturation of the protein in eggsHeating the egg whites at a temperature of about 60 C-70 C resulted albumin unfold and produce a precipitate is a solid white. This sediment can not return to its original shape. Similarly, the enzyme is heated at high temperatures. The enzyme is inactive and can not work anymore as biocatalyst.4. Denaturation of the protein in the hairProtein in human hair consists of elements of cystine, which is a compound that has an element asamamino sulfide, in a fairly high percentage of the amount. Disulfide bridge of cystine-SS-is one of the main factors responsible for the various forms yangbertanggung of our hair. Straight or curly hair because the keratin molecule containing bridges disulfidayang make mampuuntuk maintain certain forms.Rebonding process involves a chemical process that changes the structure of the protein in the hair. Rebonding process produces permanent changes in the affected hair applications. But the new hair that grows from the root hair rambutakan still have the original form. So, instead of straightening hair rebonding using only ordinary physical treatment, but also using chemical treatments that alter the structure of the protein in the hair permanently. Rebonding process through a process that uses heat pencatokan. Heating resulted in breaking the bonds making up proteins, such as hydrogen bonds break.5. Use of AntibioticsProteins present in the form of three-dimensional folds, which are determined by covalent intramolecular disulfide bonds and a number of noncovalent bonds such as ionic bonding, hydrophobic, and hydrogen. This form is called the tertiary structure of the protein, which is easily disturbed by a number of chemical or physical agent, causing the protein to be not working. Examples of antibiotics which will cause denaturation of proteins, namely: Group tetracyclines, macrolides Group.
E. REFERENCES
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• Stoker, H. Stephen. 2010. General, Organic, And Biol• Sumardjo Damin. 2006. Introductory Chemistry Lecture Handbook of Medical Students. Jakarta: EGC Book Medical Publishers.
• Winarno, F. , 2008. Chemistry of Food and Nutrition. Bogor: MBrio Press
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• Stoker, H. Stephen. 2010. General, Organic, And Biol• Sumardjo Damin. 2006. Introductory Chemistry Lecture Handbook of Medical Students. Jakarta: EGC Book Medical Publishers.
• Winarno, F. , 2008. Chemistry of Food and Nutrition. Bogor: MBrio Press
• Chayati, I. , 2009. Food Science Instructional Materials. Faculty of Engineering UNY. Yogyakarta• Anna Poedjiadi. , 1994. Fundamentals of Biochemistry. Jakarta: UI Press
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