Expert: Florence M Rollwagen - 12/4/2008

Question
QUESTION: Do chlorophyll and haemoglobin porphyrins react with one another when introduced...is there a bond that takes place..is there redox or any other form of interaction on a molecular level.  How do similar molecular structures such as porphyrins react to one another, given they have different atom nucleus?

ANSWER: Hi Curtis:  Thanks for your question.  I looked for studies that examined the interactions of the various porphyrin molecules and couldn't find any.

Is there a reason why you're asking this?  Just for curiosity, or is there some underlying track that you're following?  That will help me answer your actual question.

FM Rollwagen, PhD

---------- FOLLOW-UP ----------

QUESTION: Thanks for responding. This question relates to the use of porphyrin synthisis..specifically in cancer treatment using photo therapy and other applications. Most porphyrins using the photosynthetic model( ie. chlorophyll..heme )creat electron transfer and oxidation ( singlet ) among each other individually does this hold true collectivelly ( mg + Fe ).

Answer
Wow, it took me a long time to research your question!  Here’s what I found out.  As you know, the porphyrins are energy excitable molecules.  Without this property, plants would not be able to harvest sunshine to make sugars in photosynthesis, hence, no animal life either.  So the answer to your specific question is: yes, all the porphyrins (Fe in heme, Mg in chlorophyll will do this).  But I'm guessing you want more information than a simple "yes"

The mechanism of photoptherapy (as I understand it) is to excite the porphyrin with a specific wavelength.  This pumps an electron into an excited state (further from the nucleus).  When the excited electron falls back into place, the energy is re-emitted as light (fluorescence).  This emitted energy can create free radicals (usually oxygen free radicals) that cause tissue damage.  Chlorophyll and heme are both biological porphyrins that can perform this function.   Other porphyrins include myoglobin (muscle) and the protoporphyrins of heme synthesis.  There are conditions of disordered heme synthesis called "porphyria" which can lead to serious sun sensitivity in persons with the gene.  If you want to look them up, just search “porphyria”.

I found some references on phototherapy using porphyrins and are listed below:  Some of these references require paid membership, but you can usually get the abstract.

http://books.google.com/books?id=LNwrH5Ms9VsC&pg=PA1723&lpg=PA1723&dq=photothera

http://www3.interscience.wiley.com/journal/120004724/abstract?CRETRY=1&SRETRY=0  (abstract only)

http://www.ymj.or.kr/1989/pdf/212.pdf

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6THR-447DFGK-1&_user=1

http://www.springerlink.com/content/9142421k4548225t/  (I think you can get this one free until the end of December)

http://www3.interscience.wiley.com/journal/120013546/abstract

PubMed search: http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&cmd=Search&Term=phototherapy%

Good review:
http://images.google.com/imgres?imgurl=http://www.u-bourgogne.fr/jpp/jpp_article

Porphyrin dimers for phototherapy:
http://www.isis-innovation.com/licensing/3096.html

Pictures are worth a thousand words:

http://www.roswellpark.org/files/1_2_1/research/ravi1.gif

http://porpax.bio.miami.edu/~cmallery/150/phts/c10x10excitation.jpg  Molecular excitation of chlorophyll (a porphyrin)

Hope this helps!  Write back if you have more questions.

FM Rollwagen, PhD