Îñíîâû áèîõèìèè
Îïðåäåëèòå òèï àìèíîêèñëîòû ñîãëàñíî ôèçèêî-õèìè÷åñêîé, ôèçèîëîãè÷åñêîé è ñòðóêòóðíîé êëàññèôèêàöèè, îõàðàêòåðèçóéòå õèìè÷åñêèå è êèñëîòíî-îñíîâíûå ñâîéñòâà. Ïðèâåäèòå ðåàêöèè ñ HCl, NaOH, HNO2, CH3OH. Íàïèøèòå ôîðìóëó àìèíîêèñëîòû â èçîýëåêòðè÷åñêîé òî÷êå, à òàêæå åå êàòèîííóþ è àíèîííóþ ôîðìû â ðàñòâîðå.  êàêîé èç óêàçàííûõ ôîðì äàííàÿ àìèíîêèñëîòà áóäåò íàõîäèòüñÿ ïðè ôèçè÷åñêèõ çíà÷åíèÿõ ðÍ â îðãàíèçìå (ðÍ = 7)?
Îòâåò: Ìåòèîíèí – ìîáèëüíûé îäíîóãëåðîäíûé ôðàãìåíò, êîòîðûé èñïîëüçóåòñÿ äëÿ ìåòèëèðîâàíèÿ áîëüøîãî ÷èñëà ðàçíûõ ñîåäèíåíèé. Íåçàìåíèìàÿ ïðîòåèíîãåííàÿ ñåðîñîäåðæàùàÿ ìîíîàìèíîêàðáîíîâàÿ àìèíîêèñëîòà ñ íåïîëÿðíûì ðàäèêàëîì (α – àìèíî – γ – ìåòèëòèîìàñëÿíàÿ êèñëîòà).
CH3 – S – (CH2)2 – CH – COOH
│
NH2
Ñîêðàùåííîå íàçâàíèå: «Ìåò».
Ôèçè÷åñêèå ñâîéñòâà – áåñöâåòíîå êðèñòàëëè÷åñêîå âåùåñòâî, õîðîøî ðàñòâîðÿåòñÿ â âîäå.
Õèìè÷åñêèå ñâîéñòâà – âñå àìèíîêèñëîòû ñîäåðæàò êàðáîêñèëüíóþ ãðóïïó, îáëàäàþùóþ êèñëîòíûìè ñâîéñòâàìè è àìèíîãðóïïó, îò êîòîðîé çàâèñÿò îñíîâíûå ñâîéñòâà.
Èçîýëåêòðè÷åñêàÿ òî÷êà – 5,74.
1) CH3 – S – (CH2)2 – CH – COOH + HCl →
│
NH2
→ CH3 – S – (CH2)2 – CH – COOH Cl -
│
+ NH2
2) CH3 – S – (CH2)2 – CH – COOH + NaOH →
│
NH2
→ CH3 – S – (CH2)2 – CH – COONa + H2O (íàòðèåâàÿ ñîëü
│ àìèíîêèñëîêèñëîòû).
NH2
3) CH3 – S – (CH2)2 – CH – COOH + ÍÎ – N = O →
│ (HNO2)
NH2
→ CH3 – S – (CH2)2 – CH – COOH + N2 + H2O
│
OH
4) CH3 – S – (CH2)2 – CH – COOH + CH3OH →
│
NH2
CH3
→ CH3 – S – (CH2)2 – CH – COOH + C = O →
│ CH3
NH2
→ CH3 – S – (CH2)2 – CH – COOH + H2O
│
N = C (CH3)2
Îäíîâðåìåííîå ïðèñóòñòâèå â ìîëåêóëå àìèíîêèñëîòû è êèñëîòíîãî è îñíîâíîãî öåíòðà ïðèâîäèò ê âîçìîæíîñòè âíóòðèìîëåêóëÿðíîãî âçàèìîäåéñòâèÿ ñ îáðàçîâàíèåì áèïîëÿðíûõ èîíîâ, èëè öâèòòåð – èîíîâ:
CH3 – S – (CH2)2 – CH – COO- + Í+ →
│
NH3
→ CH3 – S – (CH2)2 – CH – COO-
│
+ NH3
 âîäíîì ðàñòâîðå α – àìèíîêèñëîòû ñóùåñòâóþò â âèäå ðàâíîâåñíîé ñìåñè áèïîëÿðíîãî èîíà, êàòèîííîé è àíèîííîé ôîðìû:
+ - H+ + -H+
NH3 – CH – COOH → NH3 – CH – COO- → NH2 – CH – COO-
│ +H+ │ +H+ │
CH3 CH3 CH2
│ │ │
S S S
│ │ │
CH2 CH2 CH2
│ │ │
CH2 CH2 CH2
│ │ │
CH – NH2 CH – NH2 CH – NH2
│ │ │
COOH COOH COOH
Êàòèîííàÿ ôîðìà Àíèîííàÿ ôîðìà
 ñðåäå ðÍ = 7 ñóùåñòâóåò â âèäå äèïîëÿ.
¹2
Íàïèøèòå ôîðìóëû äèïåïòèäîâ è òðèïåïòèäîâ, ïîñòðîåííûõ èç îñòàòêîâ ïðèâåäåííûõ íèæå àìèíîêèñëîò. Ñäåëàéòå ïðåäïîëîæåíèå î çíà÷åíèè èçîýëåêòðè÷åñêîé òî÷êè. Ïðèâåäèòå èõ ïîëíûå íàçâàíèÿ, ñîêðàùåííûå íàçâàíèÿ.
1) Ãëóòàìèíîâàÿ êèñëîòà, ñåðèí;
2) Ñåðèí, àëàíèí, ìåòèîíèí.
1) Ãëóòàìèíîâàÿ êèñëîòà
HOOC – CH2 – CH2 – CH – COOH
│
NH2
Ñåðèí
HOCH2 – CH – COOH
│
NH2
H2O
HOOC – CH2 – CH2 – CH – COOH + HOCH2 – CH – COOH →
│ │
NH2 NH2
H2O
→ HOOC – CH2 – CH2 – CH – C + HOCH – CH – C – OH
│ ║ │ ║
NH2 O NH2 O
Ãëóòàìèëàðèíîâàÿ êèñëîòà.
Ãëó – Ñåð
ðÍi = (3,22 + 5,68) / 2 = 4,45
2) Ñåðèí
HOCH2 – CH – COOH
│
NH2
Àëàíèí
CH3 – CH – COOH
│
NH2
Ìåòèîíèí
CH3 – S – (CH2)2 – CH – COOH
│
NH2
HOCH2 – CH – COOH + CH2 – CH – COOH +
│ │ │
NH2 H NH2
- 2H2O
+ CH2 – S – (CH2)2 – CH – COOH →
│ │
H NH2
→ HOCH2 – CH – C + CH2 – CH – C +
│ ║ │ ║
NH2 O NH2 O
+ CH2 – S – CH2 – CH2 – CH – COOH
│
NH2
Ñåðèëàëàíèëìåòèîíèí Ñåð – Àëà – Ìåò
ðÍi = (5,68 + 6 + 5,74) / 3 = 5,81
¹3
Ñîñòàâüòå ôîðìóëó ñîîòâåòñòâóþùåãî òðèãëèöåðèäà, íàçîâèòå åãî. Ïðèâåäèòå ðåàêöèè ñî ñëåäóþùèìè ðåàãåíòàìè:
1) I2;
2) H2;
3) HBr.
Ðàññ÷èòàéòå éîäíîå ÷èñëî è êîëè÷åñòâî âîäîðîäà â ãðàììàõ è ëèòðàõ, íåîáõîäèìîå äëÿ ïîëíîé ãèäðîãåíèçàöèè 1 êèëîãðàììà ýòîãî æèðà (óñëîâèÿ íîðìàëüíûå).
Îñòàòîê ëèíîëåâîé è äâà îñòàòêà ëèíîëåíîâîé êèñëîò.
CH – OH C17H31COOH
│
CH2 – OH C17H29COOH
│
CH2 - OH C17H29COOH
CH – OH HO – C – H31C17
│ ║
O - 3 H2O
CH2 – OH + HO – C – H29C17 →
│ ║
O
CH2 – OH HO – C – H29C17
║
O
1 CH – O – C – C17H31
║
O
2 CH2 – O – C – C17H29
║
O
3 CH2 – O – C – C17H29
║
O
1 – ëèíîëåîèë – 2 - ëèíîëåîíèë – 3 – ëèíîëåîíèëãëèöåðèí
H2 – ãèäðîãåíèçàöèÿ.
O
║
CH – C – (CH2)6 – (CH2 – CH = CH2)2 – (CH2)4 – CH3
│ O
║
CH2 – C – (CH2)6 – (CH2 – CH = CH2)3 – (CH2)4 – CH3 + 5H2 →
│ O
║
CH2 – C – (CH2)6 – (CH2 – CH = CH2)3 – (CH2)4 – CH3
O
║
CH – C – (CH2)6 – (CH2 – CH = CH2)2 – (CH2)4 – CH3
│ O H H
║ │ │
CH – C – (CH2)6 – (CH2 – CH - CH2)3 – (CH2)4 – CH3
│ O H H
║ │ │
CH – C – (CH2)6 – (CH2 – CH - CH2)3 – (CH2)4 – CH3
Ì (Ñ57Í95Î6) = 12*5 + 95*1 + 16*6 = 875
875 ã òðèãëèöåðèäà ïðèñîåäèíÿåò 10 ã Í2
1000 ã Õ
Îòâåò: Õ = 11,43 ã Í2
V ìîëü ëþáîãî ãàçà = 22,4 ë, òî
875 ã/ìîëü òðåáóåò 5*22,4 ë Í2
1000 ã Õ1
Îòâåò: Õ1 = 128 ë Í2
Éîäíîå ÷èñëî
O
║
CH – C – (CH2)6 – (CH2 – CH = CH2)2 – (CH2)4 – CH3
│ O
║
CH2 – C – (CH2)6 – (CH2 – CH = CH2)3 – (CH2)4 – CH3 + 5I2 →
│ O
║
CH2 – C – (CH2)6 – (CH2 – CH = CH2)3 – (CH2)4 – CH3
O
║
CH – C – (CH2)6 – (CH2 – CH = CH2)2 – (CH2)4 – CH3
│ O I I
║ │ │
→ CH – C – (CH2)6 – (CH2 – CH – CH2)3 – (CH2)4 – CH3
│ O I I
║ │ │
CH – C – (CH2)6 – (CH2 – CH – CH2)3 – (CH2)4 – CH3
5 ìîëü I = 1270 (Ì (I2) = 254 ã / ìîëü)
875 ã æèðà ïðèñîåäèíÿåò 5*254 ã I
10 ã Õ2
Îòâåò: Õ2 = 145,14
Ðåàêöèÿ ñ HBr.
O
||
CH - C - (CH2)6 - (CH2 - CH = CH2)2 - (CH2)4 - CH3
O
| ||
CH2 - C - (CH2)6 - (CH2 - CH = CH2)3 - (CH2)4 - CH3 + 5HBr →
O
| ||
CH2 - C - (CH2)6 - (CH2 - CH = CH2)3 - (CH2)4 - CH3
O
||
CH - C - (CH2)6 - (CH2 - CH = CH2)2 - (CH2)4 - CH3
O HBr HBr
| || | |
→ CH2 - C - (CH2)6 - (CH2 - CH - CH2)3 - (CH2)4 - CH3
O HBr HBr
| || | |
CH2 - C - (CH2)6 - (CH2 - CH - CH2)3 - (CH2)4 - CH3
¹4
Íàçîâèòå ñëåäóþùèå òðèãëèöåðèäû è ïðîäóêòû èõ ãèäðîëèçà â ùåëî÷íîé è íåéòðàëüíîé ñðåäå. Ïðèâåäèòå óðàâíåíèÿ ñîîòâåòñòâóþùèõ ðåàêöèé.
