400-998-5282
專注多肽 服務(wù)科研
編號:118154
CAS號:1816258-61-3
單字母:Biotinyl-SCNTATCVTHRLAGLLSRSGGVVKDNFVPTNVGSEAF-CONH2(Disulfide Bridge:C2-C7)
編號: | 118154 |
中文名稱: | 降鈣素Biotinyl-α-CGRP (mouse, rat) |
英文名: | Biotinyl-α-CGRP (mouse, rat) |
CAS號: | 1816258-61-3 |
單字母: | Biotinyl-SCNTATCVTHRLAGLLSRSGGVVKDNFVPTNVGSEAF-CONH2(Disulfide Bridge:C2-C7) |
三字母: | Biotinyl-Ser-Cys-Asn-Thr-Ala-Thr-Cys-Val-Thr-His-Arg-Leu-Ala-Gly-Leu-Leu-Ser-Arg-Ser-Gly-Gly-Val-Val-Lys-Asp-Asn-Phe-Val-Pro-Thr-Asn-Val-Gly-Ser-Glu-Ala-Phe-CONH2(Disulfide Bridge:Cys2-Cys7) |
氨基酸個(gè)數(shù): | 37 |
分子式: | C172H276N52O54S3 |
平均分子量: | 4032.54 |
精確分子量: | 4029.96 |
等電點(diǎn)(PI): | 11.49 |
pH=7.0時(shí)的凈電荷數(shù): | 3.18 |
平均親水性: | -0.209375 |
疏水性值: | 0.15 |
消光系數(shù): | - |
來源: | 人工化學(xué)合成,僅限科學(xué)研究使用,不得用于人體。 |
鹽體系: | 可選TFA、HAc、HCl或其它 |
儲存條件: | 負(fù)80℃至負(fù)20℃ |
標(biāo)簽: | 生物素標(biāo)記肽(Biotinyl) 二硫鍵環(huán)肽 降鈣素(Calcitonins) |
專肽生物合成用于蛋白質(zhì)-蛋白質(zhì)相互作用研究的生物素化肽。盡管生物素可以在 N 端或 C 端引入(通過賴氨酸殘基),但我們建議使用 N 端修飾,因?yàn)樗杀镜?、成功率高、周轉(zhuǎn)時(shí)間短且易于操作。因?yàn)槎嚯暮铣墒菑?C 端到 N 端合成的,因此,N 端修飾是 SPPS步驟的最后一步,不需要額外的特定縮合步驟。相比之下,C 端修飾需要額外的步驟,并且通常更復(fù)雜。當(dāng)然,原則上生物素可以定位在任何地方。
生物素可以通過多種不同的接頭或間隔物與肽分離。盡管如此,還是建議包含一個(gè)靈活的間隔物,例如 Ahx(一個(gè) 6 碳接頭),以使生物素標(biāo)簽更加穩(wěn)定或靈活。
專肽生物在 N 端或 C 端提供生物素化:生物素-N 端、賴氨酸-生物素-肽中間和賴氨酸-生物素-C 端。
專肽生物還可以使用 Ahx 接頭或長碳 (LC) 接頭提供生物素化:生物素-Ahx-N 末端、Lys-Ahx-生物素-肽中間、Lys-Ahx-生物素-C-末端。
(生物素結(jié)構(gòu))
示例:
GRGDS在N端和C端標(biāo)記生物素的結(jié)構(gòu)展示。
1、GRGDS在N端標(biāo)記生物素,不增加Ahx 接頭
2、GRGDS在N端標(biāo)記生物素,增加一個(gè)Ahx 接頭
3、GRGDS在C端標(biāo)記生物素,不增加Ahx 接頭
4、GRGDS在C端標(biāo)記生物素,增加一個(gè)Ahx 接頭。
二硫鍵廣泛存在與蛋白結(jié)構(gòu)中,對穩(wěn)定蛋白結(jié)構(gòu)具有非常重要的意義,二硫鍵一般是通過序列中的2個(gè)Cys的巰基,經(jīng)氧化形成。
形成二硫鍵的方法很多:空氣氧化法,DMSO氧化法,過氧化氫氧化法等。
二硫鍵的合成過程, 可以通過Ellman檢測以及HPLC檢測方法對其反應(yīng)進(jìn)程進(jìn)行監(jiān)測。
如果多肽中只含有1對Cys,那二硫鍵的形成是簡單的。多肽經(jīng)固相或液相合成,然后在pH8-9的溶液中進(jìn)行氧化。
當(dāng)需要形成2對或2對以上的二硫鍵時(shí),合成過程則相對復(fù)雜。盡管二硫鍵的形成通常是在合成方案的最后階段完成,但有時(shí)引入預(yù)先形成的二硫化物是有利于連合或延長肽鏈的。通常采用的巰基保護(hù)基有trt, Acm, Mmt, tBu, Bzl, Mob, Tmob等多種基團(tuán)。我們分別列出兩種以2-Cl樹脂和Rink樹脂為載體合成的多肽上多對二硫鍵形成路線:
二硫鍵反應(yīng)條件選擇
二硫鍵即為蛋白質(zhì)或多肽分子中兩個(gè)不同位點(diǎn)Cys的巰基(-SH)被氧化形成的S-S共價(jià)鍵。 一條肽鏈上不同位置的氨基酸之間形成的二硫鍵,可以將肽鏈折疊成特定的空間結(jié)構(gòu)。多肽分 子通常分子量較大,空間結(jié)構(gòu)復(fù)雜,結(jié)構(gòu)中形成二硫鍵時(shí)要求兩個(gè)半胱氨酸在空間距離上接近。 此外,多肽結(jié)構(gòu)中還原態(tài)的巰基化學(xué)性質(zhì)活潑,容易發(fā)生其他的副反應(yīng),而且肽鏈上其他側(cè)鏈 也可能會(huì)發(fā)生一系列修飾,因此,肽鏈進(jìn)行修飾所選取的氧化劑和氧化條件是反應(yīng)的關(guān)鍵因素, 反應(yīng)機(jī)理也比較復(fù)雜,既可能是自由基反應(yīng),也可能是離子反應(yīng)。
反應(yīng)條件有多種選擇,比如空氣氧化,DMSO氧化等溫和的氧化過程,也可以采用H2O2,I2, 汞鹽等激烈的反應(yīng)條件。
空氣氧化法: 空氣氧化法形成二硫鍵是多肽合成中最經(jīng)典的方法,通常是將巰基處于還原態(tài)的多肽溶于水中,在近中性或弱堿性條件下(PH值6.5-10),反應(yīng)24小時(shí)以上。為了降低分子之間二硫鍵形成的可能,該方法通常需要在低濃度條件下進(jìn)行。
碘氧化法:將多肽溶于25%的甲醇水溶液或30%的醋酸水溶液中,逐滴滴加10-15mol/L的碘進(jìn)行氧化,反應(yīng)15-40min。當(dāng)肽鏈中含有對碘比較敏感的Tyr、Trp、Met和His的殘基時(shí),氧化條件要控制的更精確,氧化完后,立即加入維生素C或硫代硫酸鈉除去過量的碘。 當(dāng)序列中有兩對或多對二硫鍵需要成環(huán)時(shí),通常有兩種情況:
自然隨機(jī)成環(huán): 序列中的Cys之間隨機(jī)成環(huán),與一對二硫鍵成環(huán)條件相似;
定點(diǎn)成環(huán): 定點(diǎn)成環(huán)即序列中的Cys按照設(shè)計(jì)要求形成二硫鍵,反應(yīng)過程相對復(fù)雜。在 固相合成多肽之前,需要提前設(shè)計(jì)幾對二硫鍵形成的順序和方法路線,選擇不同的側(cè)鏈 巰基保護(hù)基,利用其性質(zhì)差異,分步氧化形成兩對或多對二硫鍵。 通常采用的巰基保護(hù) 基有trt, Acm, Mmt, tBu, Bzl, Mob, Tmob等多種基團(tuán)。
Definition
Calcitonin is a 32-amino acid linear polypeptide hormone produced primarily by the parafollicular cells in humans and ultimobranchial body in many other animals1. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH). Calcitonin is a product of the CALC1 gene and is initially produced as a precursor1.
Discovery
Calcitonin was purified in 1962 by Copp and Cheney2. While it was initially considered a secretion of the parathyroid glands, it was later identified as the secretion of the C-cells of the thyroid gland 3 .
Classification
CALC1 gene belongs to a superfamily of related protein hormone precursors that includes islet amyloid precursor protein, calcitonin gene-related peptide, and the precursor of adrenomedullin 4 .
Structural Characteristics
Human calcitonin is a 32 amino acid peptide and is formed from procalcitonin (Cleavage products: Calcitonin, Katalin and a protein fragment)5. It has an N-terminal disulphide bridge and a C-terminal proline amide residue, shown to potently inhibit bone resorption5. Alternative splicing of the gene coding for calcitonin produces a distantly related peptide of 37 amino acids, called calcitonin gene-related peptide (CGRP) 5.
Mode of action
Calcitonin exerts its functions by binding to calcitonin receptor that is a G-protein coupled receptor. Upon binding, the receptor triggers the formation of cAMP, a second messenger which in turn activates various signaling pathways in the target cell (Eg: Osteoblasts) 6 .
Functions
Calcitonin is mainly involved in the metabolism of Ca and phosphorous in the cell. Calcitonin secretion is stimulated by rise in Ca levels in the body. It inhibits Ca intake by the intestine and also prevent loss of Ca from the bones during pregnancy and lactation7It also inhibits osteoclast activity in the bones8. This property of calcitonin is utilized for treatment of osteoporosis and osteoarthritis and recently has been tried for bone metastasis1.Procalcitonin is released during severe infection where it is involved in Ca homeostasis. It is also used as a marker for sepsis8.
References
1. Inzerillo AM, Zaidi M, Huang CL (2004). Calcitonin: physiological actions and clinical applications. J Pediatr Endocrinol Metab., 17(7), 931-40.
2. Copp DH, Cheney B (1962). Calcitonin-a hormone from the parathyroid which lowers the calcium-level of the blood. Nature, 193, 381–2.
3. Stevenson JC, Evans IM (1981). Pharmacology and therapeutic use of calcitonin. Drugs, 21(4), 257-72.
4. Zaidi M, Inzerillo AM, Moonga BS, Bevis PJ, Huang CL (2002). Forty years of calcitonin--where are we now? A tribute to the work of Iain Macintyre, FRS, Bone, 30(5), 655-63.
5. Andreotti G, Méndez BL, Amodeo P, Morelli MA, Nakamuta H, Motta A (2006). "Structural determinants of salmon calcitonin bioactivity: the role of the Leu-based amphipathic alpha-helix". J. Biol. Chem., 281 (34), 24193–203.
6. Purdue BW, Tilakaratne N, Sexton PM (2002). Molecular pharmacology of the calcitonin receptor. Recept. Channels, 8 (3-4), 243–55.
7. Woodrow JP, Sharpe CJ, Fudge NJ, Hoff AO, Gagel RF, Kovacs CS (2006). Calcitonin plays a critical role in regulating skeletal mineral metabolism during lactation. Endocrinology, 147(9), 4010-21.
8. BalcI C, Sungurtekin H, Gürses E, Sungurtekin U, Kaptanoglu B (2003). Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit. Crit Care, 7 (1), 85–90
Definition
Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide with potent receptor mediated vasodilatory and cardioexcitatory properties1.
Discovery
It was discovered when alternative processing of RNA transcripts from the calcitonin gene were shown to result in the production of distinct mRNAs encoding CGRP2. A human form of CGRP was isolated from thyroid tissue of patients with medullary thyroid carcinoma3.
Classification
CGRP belongs to the regulatory-peptide family that also includes adrenomedullin and amylin4.
Structural Characteristics
CGRP consists of an amino-terminal disulphide bridge linked loop between amino acids 2 and 7 followed by alpha helix between amino acids 8 and 18 and a poorly defined turn between residues 19 and 215. The carboxy and amino terminals of CGRP can interact independently with its receptors5.
Mode of action
CGRP exerts its function by binding to two G-protein coupled receptors, CGRP1 and CGRP2. One of the major functions of CGRP is vasodilation of cardiac muscles5. In order to achieve this, CGRP first binds to CGRP1 receptor which results in the production of cAMP which in turn activates Protein Kinase A (PKA)6. PKA phosphorylates and opens potassium channels that cause relaxation of muscles6.
Functions
CGRP is widely distributed in the central and peripheral nervous systems5. It produces vascular relaxation via binding to CGRP1 receptor5. Studies in mice have shown that CGRP may play a role in controlling blood pressure5. CGRP also protects tissue injury through its vasodilatory functions. Through its activity as a vasodilator, CGRP influence the activity of inflammatory cells by recruiting more cells at the site of inflammation7. CGRP plays a role in migraine as it is found that its levels raise during painful phases of the disease8. CGRP plays a protective role in cardiac tissue. The infusion of CGRP is beneficial in increasing cardiac output and lowering blood pressure in patients with congestive heart failure5.
References
1. Tortorella C, Macchi C, Forneris M and Nussdorfer GG (2001). Calcitonin gene-related peptide (CGRP), acting via CGRP type 1 receptors, inhibits potassium-stimulated aldosterone secretion and enhances basal catecholamine secretion from rat adrenal gland. Int. J Mol. Med., 8(3), 261-4.
2. Amara SG, Jonas V, Rosenfeld MG, Ong ES and Evans RM (1982). Alternative RNA processing in calcitonin gene expression generates mRNAs encoding different polypeptide products. Nature, 298, 240–244.
3. Aiyar N, Rand K, Elshourbagy NA, Zeng Z, Adamou JE, Bergsma DJ, and Li Y (1996). A cDNA encoding the Calcitonin Generelated peptide type 1 receptor. J Biol Chem., 271, 11325–11329.
4. Bell D and McDermott BJ (1996). Calcitonin gene-related peptide in the cardiovascular system: characterization of receptor populations and their (patho)physiological significance. Pharmacol Rev., 48, 253–288.
5. Susan DB and Andrew DG (2004). Vascular Actions of Calcitonin Gene-Related Peptide and Adrenomedullin. Physiol Rev., 84, 903-934.
6. Hirata Y, Takagi Y, Takata S, Fukuda Y, Yoshimi H, and Fujita T (1988). Calcitonin gene-related peptide receptor in cultured vascular smooth muscle and endothelial cells. Biochem Biophys Res Commun., 151, 1113–1121.
7. Lambrecht BN (2001). Immunologists getting nervous: neuropeptides, dendritic cells and T cell activation. Respir Res., 2, 133–138.
8. Durham, P (2006). Calcitonin gene-related peptide (CGRP) and migraine. Headache, 48: S3–8.