This is a working overview of Working solution, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-10-16 and is reviewed periodically as new material appears.
Identity and purity are established with reversed-phase high-performance liquid chromatography, often paired with mass spectrometry for confirmation of the expected mass. Peptide mapping after enzymatic digestion verifies the primary sequence and detects substitutions. Size-exclusion chromatography quantifies aggregates and fragments, which are the impurities most often tracked for peptides of this size. Residual solvents, counterions, and water content fall under separate tests described in pharmacopeial chapters. Circular dichroism or nuclear magnetic resonance may be used in research settings to probe secondary structure, though such methods are less common in routine release testing.
Peptide active ingredients of this type are typically supplied as lyophilized powder because the dry form resists hydrolysis during transport. The material is hygroscopic, so vials are usually equilibrated to room temperature before opening to avoid condensation on the solid. Repeated freeze-thaw cycles can promote aggregation and are generally avoided by aliquoting stock into single-use portions. Personnel handling the powder work in controlled environments to limit inhalation of fine particles. Written procedures usually specify these steps rather than leaving them to individual judgment.
Cold-chain handling is standard for formulated product, with dry powder stored frozen and ready-to-use solutions refrigerated. Light exposure is minimized because photodegradation of certain amino acid side chains is possible. Shipping and temperature-excursion studies are used to establish whether short deviations affect quality attributes. Documentation supplied with research material usually includes a certificate of analysis listing purity, identity confirmation, and water or residual solvent content. Users are expected to confirm that material meets the stated specification before use.
Identity and purity of tirzepatide are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Because the molecule carries several modifications, gradient conditions are adjusted to resolve the intact peptide from deamidation and oxidation products. Enzymatic digestion followed by peptide mapping confirms the primary sequence and locates specific modifications. Quantitation in biological matrices typically uses liquid chromatography with tandem mass spectrometry after solid-phase extraction. Immunoassays are used less often, since antibody cross-reactivity with closely related peptides can bias results.
| Property | Value | Notes |
|---|---|---|
| Typical supplied form | Lyophilized powder | Hygroscopic, seal promptly after opening |
| Long-term storage temperature | At or below minus 20 C | Protect from repeated freeze-thaw |
| Working solution stability | Hours when refrigerated | Use within the same working day |
| Primary purity method | Reversed-phase HPLC | Often paired with mass spectrometry |
| Aggregate measurement | Size-exclusion chromatography | Reports high-molecular-weight species |
当前公开资料把 tirzepatide 归为肠促胰素类受体双重激动剂。它并非激素天然变体，而是经过序列改造的工程化肽。其分子量、等电点与疏水性等基础参数已在药典和化学数据库中收录，可作为分析检测和质量研究的参照。
Tirzepatide 是一种由 39 个氨基酸组成的合成肽，分子结构上以 GIP 序列为骨架并引入脂肪酸侧链修饰，使其能够同时与葡萄糖依赖性促胰岛素多肽（GIP）受体和胰高血糖素样肽-1（GLP-1）受体结合。这种双重激动特性使它在同类肽类药物中区别于选择性 GLP-1 受体激动剂。该分子最早由一家制药公司在 2010 年代报道，随后进入糖尿病与体重管理领域的临床研究。
在生理层面，GIP 与 GLP-1 均为肠道内分泌细胞分泌的肠促胰素，进食后参与胰岛素分泌调节与胃排空抑制。Tirzepatide 通过同时激活这两条信号通路，使胰岛素分泌的葡萄糖依赖性增强，并延缓冲胃排空、降低食欲信号。与单一 GLP-1 激动相比，双靶点作用在血糖控制和体重变化上的效应幅度更大，但具体贡献比例仍在研究之中。
Development began in the 2010s, when researchers modified a GIP-based scaffold to add GLP-1 activity and then attached the fatty diacid to lengthen its half-life. Clinical evaluation proceeded through large phase 3 programmes in type 2 diabetes and in obesity, and regulators in the United States cleared the compound for type 2 diabetes in 2022 and for chronic weight management in 2023. Several cardiovascular and metabolic outcome studies are still reporting, so the picture of long-term benefit and risk is incomplete. Approvals in other regions followed on different timelines.
Tirzepatide is a synthetic peptide of 39 amino acids that carries a C20 fatty diacid side chain attached through a linker. Its molecular formula is C225H348N48O68, and its molecular weight is about 4813 daltons. The compound belongs to the incretin mimetic class and is administered by subcutaneous injection. The fatty acid chain promotes binding to serum albumin, which slows renal clearance and extends the circulation time of the molecule. It was identified during screening of sequences derived from glucose-dependent insulinotropic polypeptide.
Tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor, making it a dual agonist rather than a selective agent. Engagement of the GLP-1 receptor is linked to glucose-dependent insulin release, slower gastric emptying, and reduced appetite signalling. The relative contribution of the GIP arm remains an active research question; proposed roles include improved insulin sensitivity and altered adipose tissue handling. Receptor occupancy studies suggest the molecule interacts with both targets at circulating concentrations achieved during therapy.
Verification of research-grade material involves checking purity, sequence and counter-ion content against a certificate of analysis. Reported purity figures usually reflect chromatographic area percentage and do not by themselves establish biological activity. Independent laboratories may repeat mass confirmation and peptide mapping to detect substitutions or truncations. Open questions concern how residual solvents, trace metals and subtle conformational variants affect measured behavior, and how consistently different suppliers define their specifications. Documentation of analytical methods matters as much as the headline purity number when results are compared across studies.
Routine characterization relies on reversed-phase high-performance liquid chromatography, often coupled to mass spectrometry, to confirm identity and estimate purity. Peptide mapping after enzymatic digestion verifies the amino acid sequence and locates appended groups such as the fatty acid chain. Size-exclusion chromatography detects aggregates and fragments, while ion-exchange chromatography resolves charge variants. Circular dichroism and nuclear magnetic resonance supply secondary and higher-order structural information in research settings. No single technique covers every attribute, so laboratories combine orthogonal methods and compare outcomes against a reference standard where one exists.
Purified material is typically handled as a lyophilized powder kept at or below minus twenty degrees Celsius, shielded from light and moisture. In that state the solid remains stable for extended periods, although repeated freeze-thaw cycling can encourage aggregation. Once dissolved, aqueous solutions are less durable and are generally held cold and used within a brief window. Buffer composition, pH and ionic strength all influence degradation rates, and mildly acidic to neutral conditions are commonly examined. Actual shelf life depends on formulation, concentration and container, so stability limits are established experimentally rather than assumed.
Long-term storage of lyophilised peptide powder is generally at minus twenty degrees Celsius or colder, with desiccant and protection from light. Short-term storage at two to eight degrees Celsius is common during active use. In solution, stability depends strongly on pH, concentration, and the presence of preservatives, and hydrolysis or aggregation can develop over weeks. Published stability data specific to this molecule are limited, so recommended conditions for research material are usually extrapolated from general peptide handling practice rather than from a dedicated study.
Bulk peptide material is normally characterised by reversed-phase high-performance liquid chromatography, which separates the target sequence from truncation products and other closely related impurities. Ultraviolet detection near 214 nanometres is common because the peptide backbone absorbs in that region. Mass spectrometry, usually electrospray ionisation coupled to a mass analyser, is used to confirm the molecular mass. Because the molecule carries a lipophilic side chain, gradient methods often need a relatively high organic modifier fraction to elute it within a practical retention window.
Like most synthetic peptides of this size, the material is commonly supplied as a lyophilised powder that appears white to off-white. It dissolves in aqueous buffers and in mixtures of water with a small proportion of organic solvent, though the fatty acid portion reduces solubility in pure water relative to short peptides. Hygroscopic behaviour is reported for many peptide powders, so weighing is usually performed quickly and under controlled humidity. Working solutions are typically prepared fresh and kept cold.
After drug withdrawal, the effects fade away slowly, but may persist for more than 6–12 weeks after cessation of AAS use. Strength improvements in the range of 5 to 20% of baseline strength, depending largely on the drugs and dose used as well as the administration period. Overall, the exercise where the most significant improvements were observed is the bench press. For almost two decades, it was assumed that AAS exerted significant effects only in experienced strength athletes. A randomized controlled trial demonstrated, however, that even in novice athletes a 10-week strength training program accompanied by testosterone enanthate at 600 mg/week may improve strength more than training alone does. This dose is sufficient to significantly improve lean muscle mass relative to placebo even in subjects that did not exercise at all. The anabolic effects of testosterone enanthate were highly dose dependent.
A peptide bond forms between the amino acid attached to the tRNA in the P site and the amino acid attached to a tRNA in the A site. The formation of a peptide bond requires an input of energy. The two reacting molecules are the alpha amino group of one amino acid and the alpha carboxyl group of the other amino acids. A by-product of this bond formation is the release of water (the amino group donates a proton while the carboxyl group donates a hydroxyl). Translation can be downregulated by miRNAs (microRNAs). These RNA strands can cleave mRNA strands they are complementary to and will thus stop translation. Translation can also be regulated via helper proteins. For example, a protein called eukaryotic initiation factor-2 (eIF-2) can bind to the smaller subunit of the ribosome, starting translation. When elF-2 is phosphorylated, it cannot bind to the ribosome and translation is halted.
=== Cardiovascular system === KORs are expressed in human cardiac tissue, including cardiomyocytes, where they exert negative inotropic and lusitropic effects through pertussis toxin-sensitive Gi/o protein signaling.
=== Biosynthesis === Met-enkephalin is synthesized from proenkephalin via proteolytic cleavage in two metabolic steps. Proenkephalin A is first reduced by either one of two trypsin-like endopeptidase enzymes, proprotein convertase 1 (PC1) or prohormone convertase 2 (PC2); then, the resulting intermediates are further reduced by the enzyme carboxypeptidase E (CPE; previously known as enkephalin convertase (EC)). Proenkephalin A contains four sequences of met-enkephalin (at the following positions: 100–104; 107–111; 136–140; 210–214), and as a result, its cleavage generates four copies of met-enkephalin peptides at once. In addition, anabolism of proenkephalin A results in the production of one copy each of two C-terminal-extended met-enkephalin derivatives, the heptapeptide met-enkephalin-arg-phe (261–267), and the octapeptide met-enkephalin-arg-gly-leu (186–193), though whether they affect the opioid receptors in a similar manner as met-enkephalin is not entirely clear.
The yellow pulp, which contains the seeds, is naturally sweet and is processed into a valuable carbohydrate food. The seeds are processed into a seasoning, known as sikomu and dodowa/ dawadawa among the Yoruba and Hausa people respectively, and sunbala in the Inner Niger Delta. The pulp is also used to make beverages. The seeds of the locust bean are the most valuable part of the plant. They are high in lipids (29%), protein (35%), carbohydrates (16%), and are a good source of fat and calcium for rural dwellers. The seed is first cooked to remove the seed coat and then fermented to produce the desired result. Seeds can then be pounded into powder, then formed into cakes. In a study conducted on the fermentation of dawadawa, it was found that Gmelina arborea and banana leaves accelerated fermentation of seeds, while increasing fat, protein and moisture content, but also decreasing carbohydrate content.
Sources: en.wikipedia.org
== Science, technology and engineering == Laser direct structuring, a manufacturing method LDS fluid, a Citroën hydraulic fluid LDS (automobile), South African racing cars Leak detection system, for fluids Lipodermatosclerosis, a skin and connective tissue disease, affecting the lower extremities Lymphedema–distichiasis syndrome, a genetic disorder of eyelashes and lymphatic system Loeys–Dietz syndrome, a genetic disorder affecting connective tissue LDS-1 (Line Drawing System-1), an early computer graphics system
The U.S. Department of Energy (DOE) has published a list of yearly technical system targets for on-board hydrogen storage for light-duty fuel cell vehicles which guide researchers in the field (5.5 wt %/40 g L−1 by 2017; 7.5 wt %/70 g L−1 ultimate). Materials with high porosity and high surface area such as MOFs have been designed and synthesized in an effort to meet these targets. These adsorptive materials generally work via physical adsorption rather than chemisorption due to the large HOMO–LUMO gap and low HOMO energy level of molecular hydrogen. A benchmark material to this end is MOF-177 which was found to store hydrogen at 7.5 wt % with a volumetric capacity of 32 g L−1 at 77 K and 70 bar. MOF-177 consists of [Zn4O]6+ clusters interconnected by 1,3,5-benzenetribenzoate organic linkers and has a measured BET surface area of 4630 m2 g−1. Another exemplary material is PCN-61 which exhibits a hydrogen uptake of 6.24 wt % and 42.5 g L−1 at 35 bar and 77 K and 2.25 wt % at atmospheric pressure. PCN-61 consists of [Cu2]4+ paddle-wheel units connected through 5,5′,5′′-benzene-1,3,5-triyltris(1-ethynyl-2-isophthalate) organic linkers and has a measured BET surface area of 3000 m2 g−1. Despite these promising MOF examples, the classes of synthetic porous materials with the highest performance for practical hydrogen storage are activated carbon and covalent organic frameworks (COFs).
These latter amino acids are therefore termed "ketogenic" amino acids, whereas those that enter the citric acid cycle as intermediates can only be cataplerotically removed by entering the gluconeogenic pathway via malate which is transported out of the mitochondrion to be converted into cytosolic oxaloacetate and ultimately into glucose. These are the so-called "glucogenic" amino acids. De-aminated alanine, cysteine, glycine, serine, and threonine are converted to pyruvate and can consequently either enter the citric acid cycle as oxaloacetate (an anaplerotic reaction) or as acetyl-CoA to be disposed of as CO2 and water. In fat catabolism, triglycerides are hydrolyzed to break them into fatty acids and glycerol. In the liver the glycerol can be converted into glucose via dihydroxyacetone phosphate and glyceraldehyde-3-phosphate by way of gluconeogenesis. In skeletal muscle, glycerol is used in glycolysis by converting glycerol into glycerol-3-phosphate, then into dihydroxyacetone phosphate (DHAP), then into glyceraldehyde-3-phosphate. In many tissues, especially heart and skeletal muscle tissue, fatty acids are broken down through a process known as beta oxidation, which results in the production of mitochondrial acetyl-CoA, which can be used in the citric acid cycle. Beta oxidation of fatty acids with an odd number of methylene bridges produces propionyl-CoA, which is then converted into succinyl-CoA and fed into the citric acid cycle as an anaplerotic intermediate.
. The mechanics of contacting rough surfaces are discussed in terms of normal contact mechanics and static frictional interactions. Natural and engineering surfaces typically exhibit roughness features, known as asperities, across a broad range of length scales down to the molecular level, with surface structures exhibiting self affinity, also known as surface fractality. It is recognized that the self affine structure of surfaces is the origin of the linear scaling of true contact area with applied pressure. Assuming a model of shearing welded contacts in tribological interactions, this ubiquitously observed linearity between contact area and pressure can also be considered the origin of the linearity of the relationship between static friction and applied normal force. In contact between a "random rough" surface and an elastic half-space, the true contact area is related to the normal force
=== Relation to the WH2 sequence module === The N-terminal half of β-thymosins bears a strong similarity in amino acid sequence to a very widely distributed sequence module, the WH2 module. (Wasp Homology Domain 2 - the name is derived from Wiskott-Aldrich syndrome protein). Evidence from X-ray crystallography shows that this part of β-thymosins binds to actin in a near-identical manner to that of WH2 modules, both adopting as they bind, a conformation which has been referred to as the β-thymosin/WH2 fold. β-thymosins may therefore have evolved by addition of novel C-terminal sequence to an ancestral WH2 module. However, sequence similarity searches designed to identify present-day WH2 domains fail to recognise β-thymosins, (and vice versa) and the sequence and functional similarities may result from convergent evolution.
Sources: en.wikipedia.org
Water promotes hydrolysis and deamidation, so removing it slows degradation during transport and storage. The dry solid is also less prone to microbial growth than a solution. Reconstitution is therefore performed close to the point of use.
Reversed-phase high-performance liquid chromatography is the standard method for purity and related substances. It separates the main peak from deletion sequences and oxidation products. Mass spectrometry is frequently used alongside it to confirm molecular identity.
Aggregates, truncated sequences, and oxidation products receive the most attention. Size-exclusion chromatography covers aggregates, while reversed-phase methods resolve many chemical variants. Limits are set according to the route of administration and the expected exposure.
Reversed-phase liquid chromatography with ultraviolet detection is the usual approach, frequently combined with mass spectrometry for identity. Purity is reported as the area percentage of the main peak. Related impurities eluting near the main peak are usually summed and reported separately.