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Hemin

Hemin is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hemin rather than just read about it. In short: Hemin (haemin; ferric chloride heme; ferriprotoporphyrin IX chloride) is an iron-containing porphyrin with chlorine that can be formed from a heme group, such as heme B found in the hemoglobin of human blood. Chemistry Hemin is protoporphyrin IX containing a ferric iron (Fe3+) ion with a coordinating chloride ligand.

Hemin — main illustration
Hemin — illustration

Key takeaways

  • Hemin belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Hemin to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Hemin from memory before moving on to harder problems.

Reference excerpt

Hemin (haemin; ferric chloride heme; ferriprotoporphyrin IX chloride) is an iron-containing porphyrin with chlorine that can be formed from a heme group, such as heme B found in the hemoglobin of human blood.

Chemistry Hemin is protoporphyrin IX containing a ferric iron (Fe3+) ion with a coordinating chloride ligand. Hemin is a dark brown solid that is almost insoluble in water, but soluble in alkaline aqueous solutions to form a dark green aqueous solution of hematin. Chemically, hemin differs from the related heme-compound hematin chiefly in that the coordinating ion is a chloride ion in hemin, whereas the coordinating ion is a hydroxide ion in hematin. The iron ion in haem is ferrous (Fe2+), whereas it is ferric (Fe3+) in both hemin and hematin. Hemin is endogenously produced in the human body, for example during the turnover of old red blood cells. It can form inappropriately as a result of hemolysis or vascular injury. Several proteins in human blood bind to hemin, such as hemopexin and serum albumin. Hemin reacts with hydrogen cyanide in ammonia solution to form a blood-red complex.

Pharmacological use A lyophilised form of hemin is used as a pharmacological agent in certain cases for the treatment of porphyria attacks, particularly in acute intermittent porphyria. Administration of hemin can reduce heme deficits in such patients, thereby suppressing the activity of delta-amino-levulinic acid synthase (a key enzyme in the synthesis of the porphyrins) by biochemical feedback, which in turn reduces the production of porphyrins and of the toxic precursors of heme. In such pharmacological contexts, hemin is typically formulated with human albumin prior to administration by a medical professional, to reduce the risk of phlebitis and to stabilize the compound, which is potentially reactive if allowed to circulate in free-form. Such pharmacological forms of hemin are sold under a range of trade names including the trademarks Panhematin and Normosang.

History of isolation Hemin was first crystallized out of blood in 1853, by Ludwik Karol Teichmann. Teichmann discovered that blood pigments can form microscopic crystals. Thus, crystals of hemin are occasionally referred to as 'Teichmann crystals'. Hans Fischer synthesized hemin, for which he was awarded the Nobel Prize in Chemistry in 1930. Fischer's procedure involves treating defibrinated blood with a solution of sodium chloride in acetic acid.

Forensics Hemin can be produced from hemoglobin by the so-called Teichmann test, when hemoglobin is heated with glacial acetic acid (saturated with saline). This can be used to detect blood traces.

Other Hemin is considered the "X factor" required for the growth of Haemophilus influenzae.

References

External links Hemin at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Illustrations

Hemin illustration
Hemin illustration
Hemin: The color change of hemin in ammonia solution upon contact with hydrogen cyanide. Left: hemin in ammonia solution, dark green to blackish brown; Right: After reacting with hydrogen cyanide, it turns blood red.
The color change of hemin in ammonia solution upon contact with hydrogen cyanide. Left: hemin in ammonia solution, dark green to blackish brown; Right: After reacting with hydrogen cyanide, it turns blood red.

Worked examples

Example 1 — a first encounter with Hemin

Start with the simplest possible case. Write down what Hemin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hemin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hemin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hemin

In research
Hemin appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Hemin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Hemin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Orphan drugs, Porphyrins, so understanding it makes those chapters shorter.
In everyday life
Look for Hemin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hemin in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Hemin means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Hemin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hemin in simple terms?

Hemin (haemin; ferric chloride heme; ferriprotoporphyrin IX chloride) is an iron-containing porphyrin with chlorine that can be formed from a heme group, such as heme B found in the hemoglobin of human blood. Chemistry Hemin is protoporphyrin IX containing a ferric iron (Fe3+) ion with a coordinati…

Why does Hemin matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hemin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hemin.

Tags

  • Orphan drugs
  • Porphyrins

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