أحماض أمينية مركبة للپروتينات
الأحماض الأمينية المركبة للپروتينات Proteinogenic amino acids، هي الأحماض الأمينية التي أُدمجت حيوياً في الپروتينات أثناء الترجمة. في جميع أشكال الحياة المعروفة، يوجد 22 حمض أميني مكون للپروتين مشفر وراثياً، 20 في الشفرة الوراثية القياسية و2 إضافيين يمكن دمجهما عبر آليات ترجمة خاصة.
الهجريب
-ألانين
(Ala / A)-أرجينين
(Arg / R)-أسپاراجين
(Asn / N)-حمض الأسپارتيك
(Asp / D)-سيستين
(Cys / C)-حمض الگلوتاميك
(Glu / E)-گلوتامين
(Gln / Q)گليسين
(Gly / G)-هيستيدين
(His / H)-إيسولوسين
(Ile / I)-لوسين
(Leu / L)-ليسين
(Lys / K)-ميثيونين
(Met / M)-فنايلألانين
(Phe / F)-پرولين
(Pro / P)-سيرين
(Ser / S)-ثريونين
(Thr / T)-تريپتوفان
(Trp / W)-تيروسين
(Tyr / Y)-ڤالين
(Val / V)
-سلنوسيتين
(Sec / U)-پيروليسين
(Pyl / O)
الخصائص الكيميائية
الخصائص الكيميائية العامة
الحمض الأميني | الاختصار | الرمز | الكتلة الذرية (دالتون) | نقطة التعادل الكهربائي pI |
ثابت انحلال الهيدوكسيل pK1 |
ثابت انحلال الأمين pK2 |
---|---|---|---|---|---|---|
ألانين | A | Ala | 89.09404 | 6.01 | 2.35 | 9.87 |
سيستين | C | Cys | 121.15404 | 5.05 | 1.92 | 10.70 |
حمض الأسپارتيك | D | Asp | 133.10384 | 2.85 | 1.99 | 9.90 |
حمض الگلوتاميك | E | Glu | 147.13074 | 3.15 | 2.10 | 9.47 |
فنايلألانين | F | Phe | 165.19184 | 5.49 | 2.20 | 9.31 |
گليسين | G | Gly | 75.06714 | 6.06 | 2.35 | 9.78 |
هيستيدين | H | His | 155.15634 | 7.60 | 1.80 | 9.33 |
إيسولوسين | I | Ile | 131.17464 | 6.05 | 2.32 | 9.76 |
ليسين | K | Lys | 146.18934 | 9.60 | 2.16 | 9.06 |
لوسين | L | Leu | 131.17464 | 6.01 | 2.33 | 9.74 |
مثيونين | M | Met | 149.20784 | 5.74 | 2.13 | 9.28 |
أسپاراجين | N | Asn | 132.11904 | 5.41 | 2.14 | 8.72 |
پيروليسين | O | Pyl | 255.31 | |||
پرولين | P | Pro | 115.13194 | 6.30 | 1.95 | 10.64 |
گلوتامين | Q | Gln | 146.14594 | 5.65 | 2.17 | 9.13 |
أرجنين | R | Arg | 174.20274 | 10.76 | 1.82 | 8.99 |
سيرين | S | Ser | 105.09344 | 5.68 | 2.19 | 9.21 |
ثريونين | T | Thr | 119.12034 | 5.60 | 2.09 | 9.10 |
سيلينوسيستين | U | Sec | 168.053 | 5.47 | 1.91 | 10 |
ڤالين | V | Val | 117.14784 | 6.00 | 2.39 | 9.74 |
تريپتوفان | W | Trp | 204.22844 | 5.89 | 2.46 | 9.41 |
تيروسين | Y | Tyr | 181.19124 | 5.64 | 2.20 | 9.21 |
خصائص السلسلة الجانبية
الحمض الأميني | الاختصار | الرمز | السلسة الجانبية | للماء | pKa§ | قطبية | pH | صغيرة | دقيقة |
عطرية أوأليفاتية |
volume (Å3) |
---|---|---|---|---|---|---|---|---|---|---|---|
ألانين | A | Ala | -CH3 | X | - | - | - | X | X | أليفاتية | 67 |
سيستين | C | Cys | -CH2SH | X | 8.55 | - | حمضية | X | X | - | 86 |
حمض الأسپارتيك | D | Asp | -CH2COOH | - | 3.67 | X | حمضية | X | - | - | 91 |
حمض الگلوتاميك | E | Glu | -CH2CH2COOH | - | 4.25 | X | حمضية | - | - | - | 109 |
فنايلألانين | F | Phe | -CH2C6H5 | X | - | - | - | - | - | عطرية | 135 |
گليسين | G | Gly | -H | X | - | - | - | X | X | - | 48 |
هيستيدين | H | His | -CH2- | - | 6.54 | X | قاعدية ضعيفة | - | - | عطرية | 118 |
إيزوليوسين | I | Ile | -CH(CH3)CH2CH3 | X | - | - | - | - | - | أليفاتية | 124 |
ليسين | K | Lys | -(CH2)4NH2 | - | 10.40 | X | قاعدية | - | - | - | 135 |
ليوسين | L | Leu | -CH2CH(CH3)2 | X | - | - | - | - | - | أليفاتية | 124 |
مثيونين | M | Met | -CH2CH2SCH3 | X | - | - | - | - | - | أليفاتية | 124 |
أسپاراجين | N | Asn | -CH2CONH2 | - | - | X | - | X | - | - | 96 |
پيروليسين | O | Pyl | -(CH2)4NCH3 | - | N.D. | X | قاعدية ضعيفة | - | - | - | |
پرولين | P | Pro | -CH2CH2CH2- | X | - | - | - | X | - | - | 90 |
گولتامين | Q | Gln | -CH2CH2CONH2 | - | - | X | - | - | - | - | 114 |
أرجينين | R | Arg | -(CH2)3NH-C(NH)NH2 | - | 12.3 | X | قاعدية قوية | - | - | - | 148 |
سيرين | S | Ser | -CH2OH | - | - | X | - | X | X | - | 73 |
ثريونين | T | Thr | -CH(OH)CH3 | - | - | X | - | X | - | - | 93 |
سيلنوسيستين | U | Sec | -CH2SeH | - | 5.43 | - | حمضية | X | X | - | |
ڤالين | V | Val | -CH(CH3)2 | X | - | - | - | X | - | أليفاتية | 105 |
تريپتوفان | W | Trp | -CH2N | - | - | X | - | - | - | عطرية | 163 |
تيروسين | Y | Tyr | -CH2-C6H4OH | - | 9.84 | X | حمضية ضعيفة | - | - | عطرية | 141 |
التعبير الجيني والكيمياء الحيوية
الحمض الأميني | الاختصار | الرمز | الشفرات | التواجد
في پروتينات العتائق (%)& |
التوجد
في پروتينات الجراثيم (%)& |
التوجد
في پروتينات حقيقيات النوى (%)& |
التواجد في الپروتينات البشرية (%)& |
Essential‡ في البشر |
---|---|---|---|---|---|---|---|---|
ألانين | A | Ala | GCU, GCC, GCA, GCG | 8.2 | 10.06 | 7.63 | 7.01 | لا |
سيستين | C | Cys | UGU, UGC | 0.98 | 0.94 | 1.76 | 2.3 | مشروط |
حمض الأسپارتيك | D | Asp | GAU, GAC | 6.21 | 5.59 | 5.4 | 4.73 | No |
حمض الگلوتاميك | E | Glu | GAA, GAG | 7.69 | 6.15 | 6.42 | 7.09 | مشروط |
فنايلألانين | F | Phe | UUU, UUC | 3.86 | 3.89 | 3.87 | 3.65 | نعم |
گليسين | G | Gly | GGU, GGC, GGA, GGG | 7.58 | 7.76 | 6.33 | 6.58 | مشروط |
هيستيدين | H | His | CAU, CAC | 1.77 | 2.06 | 2.44 | 2.63 | نعم |
إيسولوسين | I | Ile | AUU, AUC, AUA | 7.03 | 5.89 | 5.1 | 4.33 | نعم |
ليسين | K | Lys | AAA, AAG | 5.27 | 4.68 | 5.64 | 5.72 | نعم |
ليوسين | L | Leu | UUA, UUG, CUU, CUC, CUA, CUG | 9.31 | 10.09 | 9.29 | 9.97 | نعم |
مثيونين | M | Met | AUG | 2.35 | 2.38 | 2.25 | 2.13 | نعم |
أسپاراجين | N | Asn | AAU, AAC | 3.68 | 3.58 | 4.28 | 3.58 | لا |
پيروليسين | O | Pyl | UAG* | 0 | 0 | 0 | 0 | لا |
پرولين | P | Pro | CCU, CCC, CCA, CCG | 4.26 | 4.61 | 5.41 | 6.31 | لا |
گلوتامين | Q | Gln | CAA, CAG | 2.38 | 3.58 | 4.21 | 4.77 | لا |
أرجنين | R | Arg | CGU, CGC, CGA, CGG, AGA, AGG | 5.51 | 5.88 | 5.71 | 5.64 | مشروط |
سيرين | S | Ser | UCU, UCC, UCA, UCG, AGU, AGC | 6.17 | 5.85 | 8.34 | 8.33 | لا |
ثريونين | T | Thr | ACU, ACC, ACA, ACG | 5.44 | 5.52 | 5.56 | 5.36 | نعم |
Selenocysteine | U | Sec | UGA** | 0 | 0 | 0 | >0 | لا |
ڤالين | V | Val | GUU, GUC, GUA, GUG | 7.8 | 7.27 | 6.2 | 5.96 | نعم |
تريپتوفان | W | Trp | UGG | 1.03 | 1.27 | 1.24 | 1.22 | نعم |
تيروسين | Y | Tyr | UAU, UAC | 3.35 | 2.94 | 2.87 | 2.66 | مشروط |
Stop codon† | - | Term | UAA, UAG, UGA†† | - | - |
مطيافية الكتلة
الحمض الأميني | الاختصار | الرمز | الصيغة | Mon. Mass§ (Da) | متوسط الكتلة (Da) |
---|---|---|---|---|---|
ألانين | A | Ala | C3H5NO | 71.03711 | 71.0779 |
سيستين | C | Cys | C3H5NOS | 103.00919 | 103.1429 |
حمض الأسپارتيك | D | Asp | C4H5NO3 | 115.02694 | 115.0874 |
حمض الگلوتاميك | E | Glu | C5H7NO3 | 129.04259 | 129.1140 |
فنايلألانين | F | Phe | C9H9NO | 147.06841 | 147.1739 |
گليسين | G | Gly | C2H3NO | 57.02146 | 57.0513 |
هيستيدين | H | His | C6H7N3O | 137.05891 | 137.1393 |
إيسولوسين | I | Ile | C6H11NO | 113.08406 | 113.1576 |
ليسين | K | Lys | C6H12N2O | 128.09496 | 128.1723 |
لوسين | L | Leu | C6H11NO | 113.08406 | 113.1576 |
مثيونين | M | Met | C5H9NOS | 131.04049 | 131.1961 |
أسپاراجين | N | Asn | C4H6N2O2 | 114.04293 | 114.1026 |
پيروليسين | O | Pyl | C12H19N3O2 | 237.14773 | 237.2982 |
پرولين | P | Pro | C5H7NO | 97.05276 | 97.1152 |
گلوتامين | Q | Gln | C5H8N2O2 | 128.05858 | 128.1292 |
أرجنين | R | Arg | C6H12N4O | 156.10111 | 156.1857 |
سيرين | S | Ser | C3H5NO2 | 87.03203 | 87.0773 |
ثريونين | T | Thr | C4H7NO2 | 101.04768 | 101.1039 |
سيلينوسيستين | U | Sec | C3H5NOSe | 150.95364 | 150.0489 |
ڤالين | V | Val | C5H9NO | 99.06841 | 99.1311 |
تريپتوفان | W | Trp | C11H10N2O | 186.07931 | 186.2099 |
تيروسين | Y | Tyr | C9H9NO2 | 163.06333 | 163.1733 |
§ Monoisotopic mass
قياس اتحادية العناصر وقيمة الأيض في الخلية
الحمض الأميني | Abundance (# of molecules (×108) per E. coli cell) |
ATP cost in synthesis under aerobic condition |
ATP cost in synthesis under anaerobic condition |
---|---|---|---|
ألانين | 2.9 | -1 | 1 |
سيستين | 0.52 | 11 | 15 |
حمض الأسپارتيك | 1.4 | 0 | 2 |
حمض الگلوتاميك | 1.5 | -7 | -1 |
فنايلألانين | 1.1 | -6 | 2 |
گليسين | 3.5 | -2 | 2 |
هيستيدين | 0.54 | 1 | 7 |
إيسولوسين | 1.7 | 7 | 11 |
ليسين | 2.0 | 5 | 9 |
لوسين | 2.6 | -9 | 1 |
مثيونين | 0.88 | 21 | 23 |
أسپاراجين | 1.4 | 3 | 5 |
پيروليسين | 1.3 | -2 | 4 |
گلوتامين | 1.5 | -6 | 0 |
أرجنين | 1.7 | 5 | 13 |
سيرين | 1.2 | -2 | 2 |
ثريونين | 1.5 | 6 | 8 |
تريپتوفان | 0.33 | -7 | 7 |
تيروسين | 0.79 | -8 | 2 |
ڤالين | 2.4 | -2 | 2 |
ملاحظات
الحمض الأميني | الرمز | ملاحظات | |
---|---|---|---|
ألانين | A | Ala | Very abundant and very versatile, it is more stiff than glycine, but small enough to pose only small steric limits for the protein conformation. It behaves fairly neutrally, and can be located in both hydrophilic regions on the protein outside and the hydrophobic areas inside. |
أسپاراجين أوحمض الأسپاراتيك | B | Asx | A placeholder when either amino acid may occupy a position |
سيستين | C | Cys | The sulfur atom bonds readily to heavy metal ions. Under oxidizing conditions, two cysteines can join together in a disulfide bond to form the amino acid cystine. When cystines are part of a protein, insulin for example, the tertiary structure is stabilized, which makes the protein more resistant to denaturation; therefore, disulfide bonds are common in proteins that have to function in harsh environments including digestive enzymes (e.g., pepsin and chymotrypsin) and structural proteins (e.g., keratin). Disulfides are also found in peptides too small to hold a stable shape on their own (e.g. insulin). |
حمض الأسپارتيك | D | Asp | Asp behaves similarly to glutamic acid, and carries a hydrophilic acidic group with strong negative charge. Usually, it is located on the outer surface of the protein, making it water-soluble. It binds to positively charged molecules and ions, and is often used in enzymes to fix the metal ion. When located inside of the protein, aspartate and glutamate are usually paired with arginine and lysine. |
حمض الگلوتاميك | E | Glu | Glu behaves similarly to aspartic acid, and has a longer, slightly more flexible side chain. |
فنايلألانين | F | Phe | Essential for humans, phenylalanine, tyrosine, and tryptophan contain a large, rigid aromatic group on the side chain. These are the biggest amino acids. Like isoleucine, leucine, and valine, these are hydrophobic and tend to orient towards the interior of the folded protein molecule. Phenylalanine can be converted into tyrosine. |
گليسين | G | Gly | Because of the two hydrogen atoms at the α carbon, glycine is not optically active. It is the smallest amino acid, rotates easily, and adds flexibility to the protein chain. It is able to fit into the tightest spaces, e.g., the triple helix of collagen. As too much flexibility is usually not desired, as a structural component, it is less common than alanine. |
هيستيدين | H | His | His is essential for humans. In even slightly acidic conditions, protonation of the nitrogen occurs, changing the properties of histidine and the polypeptide as a whole. It is used by many proteins as a regulatory mechanism, changing the conformation and behavior of the polypeptide in acidic regions such as the late endosome or lysosome, enforcing conformation change in enzymes. However, only a few histidines are needed for this, so it is comparatively scarce. |
إيسولوسين | I | Ile | Ile is essential for humans. Isoleucine, leucine, and valine have large aliphatic hydrophobic side chains. Their molecules are rigid, and their mutual hydrophobic interactions are important for the correct folding of proteins, as these chains tend to be located inside of the protein molecule. |
لوسين أوإيسولوسين | J | Xle | A placeholder when either amino acid may occupy a position |
ليسين | K | Lys | Lys is essential for humans, and behaves similarly to arginine. It contains a long, flexible side chain with a positively charged end. The flexibility of the chain makes lysine and arginine suitable for binding to molecules with many negative charges on their surfaces. E.g., DNA-binding proteins have their active regions rich with arginine and lysine. The strong charge makes these two amino acids prone to be located on the outer hydrophilic surfaces of the proteins; when they are found inside, they are usually paired with a corresponding negatively charged amino acid, e.g., aspartate or glutamate. |
لوسين | L | Leu | Leu is essential for humans, and behaves similarly to isoleucine and valine. |
مثيونين | M | Met | Met is essential for humans. Always the first amino acid to be incorporated into a protein, it is sometimes removed after translation. Like cysteine, it contains sulfur, but with a methyl group instead of hydrogen. This methyl group can be activated, and is used in many reactions where a new carbon atom is being added to another molecule. |
أسپاراجين | N | Asn | Similar to aspartic acid, Asn contains an amide group where Asp has a carboxyl. |
پيروليسين | O | Pyl | Similar to lysine, but it has a pyrroline ring attached. |
پرولين | P | Pro | Pro contains an unusual ring to the N-end amine group, which forces the CO-NH amide sequence into a fixed conformation. It can disrupt protein folding structures like α helix or β sheet, forcing the desired kink in the protein chain. Common in collagen, it often undergoes a post-translational modification to hydroxyproline. |
گلوتامين | Q | Gln | Similar to glutamic acid, Gln contains an amide group where Glu has a carboxyl. Used in proteins and as a storage for ammonia, it is the most abundant amino acid in the body. |
أرجنين | R | Arg | Functionally similar to lysine. |
سيرين | S | Ser | Serine and threonine have a short group ended with a hydroxyl group. Its hydrogen is easy to remove, so serine and threonine often act as hydrogen donors in enzymes. Both are very hydrophilic, so the outer regions of soluble proteins tend to be rich with them. |
ثريونين | T | Thr | Essential for humans, Thr behaves similarly to serine. |
سيلينوسيستين | U | Sec | The selenium analog of cysteine, in which selenium replaces the sulfur atom. |
ڤالين | V | Val | Essential for humans, Val behaves similarly to isoleucine and leucine. |
تريپتوفان | W | Trp | Essential for humans, Trp behaves similarly to phenylalanine and tyrosine. It is a precursor of serotonin and is naturally fluorescent. |
غير معروف | X | Xaa | Placeholder when the amino acid is unknown or unimportant. |
تيروسين | Y | Tyr | Tyr behaves similarly to phenylalanine (precursor to tyrosine) and tryptophan, and is a precursor of melanin, epinephrine, and thyroid hormones. Naturally fluorescent, its fluorescence is usually quenched by energy transfer to tryptophans. |
حمض الگلوتاميك أوگلوتامين | Z | Glx | A placeholder when either amino acid may occupy a position |
انظر أيضاً
- حمض أميني گلوكوجيني
- حمض أميني كيتوجيني
المصادر
- ^ Ambrogelly A, Palioura S, Söll D (Jan 2007). "Natural expansion of the genetic code". Nat Chem Biol. 3 (1): 29–35. doi:10.1038/nchembio847. PMID 17173027.
مراجع عامة
- Nelson, David L.; Cox, Michael M. (2000). Lehninger Principles of Biochemistry (3rd ed.). Worth Publishers. ISBN .
- Kyte, J.; Doolittle, R. F. (1982). "A simple method for displaying the hydropathic character of a protein". J. Mol. Biol. 157 (1): 105–132. doi:10.1016/0022-2836(82)90515-0. PMID 7108955.
- Meierhenrich, Uwe J. (2008). Amino acids and the asymmetry of life (1st ed.). Springer. ISBN .
- Biochemistry, Harpers (2015). Harpers Illustrated Biochemistry (30st ed.). Lange. ISBN .
وصلات خارجية
مشاع الفهم فيه ميديا متعلقة بموضوع Amino acids. |
- The origin of the single-letter code for the amino acids