It is the technique of using enzymes in the treatment of various genetic and
microbial diseases. This technique is considered one of the branches of Protein
Therapeutics, which forms a wide section of medical biotechnology. Although it was
not long after its discovery so it is also considered one of the sections of modern
Genetically engineered enzymes may be used as therapeutic agents. For example,
both recombinant DNase I and alginate lyase have been used in an aerosol form to
decrease the viscosity of the mucus found in the lungs of patients with cystic fibrosis.
Certain therapeutic enzymes may be delivered directly to their target cells by
expressing the genes for these proteins in a bacterium that is normally associated with
human tissues and has been shown to be safe.
Enzymes have been used as therapeutic drugs for diverse pathologies. Advances in
both biotechnology and protein engineering have shed light on the study of enzymes’
potential as therapeutic tools and on the metabolic pathways involved in different
diseases. As a result, recombinant enzymes have emerged as new treatments for many
diseases such as genetic abnormalities (LSD, CF, et cetera) and cancer, among other
To become widely used drugs, enzyme therapies must overcome enzyme rapid
clearance in vivo, the unwanted off-target interactions and patient immune response.
The encapsulation and molecular modifications of enzymes, together with active
monitoring of immune response, are the most remarkable therapy improvement
techniques addressed to date
Enzymes may be used therapeutically in a variety of ways. For example:-
• They may be used to augment an existing metabolic pathway, thereby
increasing the amount of a particular compound or metabolite that is a
product of that pathway.
• Alternatively, some enzymes may be used to relieve the disease
pressure caused by a pathogen or may help to lower the level of an
Scientists isolated the cDNA for the human enzyme deoxyribonuclease I
(DNase I) and subsequently expressed the cDNA in CHO cells in culture.
DNase I can hydrolyze long polymeric DNA chains into much shorter
The purified enzyme is delivered in an aerosol mist to the lungs of patients
with cystic fibrosis.
The DNase I decreases the viscosity and adhesivity of the mucus in the
lungs and makes it easier for these patients to breathe. While this treatment is
not a cure for cystic fibrosis, it nevertheless relieves the most severe symptom
of the disease in most patients.
Figure (1) : (A) Schematic
representation of a portion of
a human lung occluded by a
combination of live alginate-
secreting bacterial cells, lysed
bacterial cells, and leukocytes
and their released DNA being
cleared by digestion by
aerosol-delivered DNase I.
(B) Digestion of DNA by
The excretion of alginate by mucoid strains of the bacterium Pseudomonas aeruginosa
that infect the lungs of patients with cystic fibrosis significantly contributes to the viscosity
of the mucus in the airways
In which the alginate prevents added antibiotics from coming into contact with the
bacterial cells. In one experiment, it was shown that the addition of the enzyme alginate
lyase, which can liquefy bacterial alginate, together with or prior to antibiotic treatment
significantly decreased the number of bacteria found in biofilms. Thus, alginate lyase
treatment not only decreases the viscosity of the mucus but also facilitates the ability of
added antibiotics to kill the infecting bacterial cells. This result suggests that in addition to
the DNase I treatment, depolymerization of the alginate might help clear blocked airways of
individuals with cystic fibrosis.
Figure (2) : Time courses of the killing of bacteria in biofilms
with and without treatment with alginate lyase.
Is a stable enzyme that does not require a cofactor and could potentially prevent the
accumulation of phenylalanine in phenylketonuria patients.
To test this concept, the gene for phenylalanine ammonia lyase from the yeast
Rhodosporidium toruloides was cloned and overexpressed in E. coli.
Plasma phenylalanine levels were lowered when phenylalanine ammonia lyase was
injected intravenously or encapsulated enzyme was administered orally.
It act by onverts phenylalanine to ammonia and trans-cinnamic acid and this enhance the
remove of phenylalanine from patient’s body.
Figure (3) : Patients with
phenylketonuria are unable to
metabolize phenylalanine in the
liver as healthy people do.
They metabolize phenylalanine
in the intestine alternatively
through oral administration of
the engineered probiotic
The ABO blood group system is based upon the presence or absence of
specific carbohydrate residues on the surfaces of erythrocytes, endothelial
cells, and some epithelial cells.
The monosaccharide that determines blood group A is a terminal α-
while the corresponding monosaccharide of blood group B is α-1,3-
it is advantageous to have a large supply of plasma that is from blood group O (e.g.,
in an emergency situation, there may not be sufficient time to check a patient’s blood
group). Fortunately, digestion of specific carbohydrate residues on the surfaces blood
cells from either type A or B with specific glycosidases can cause types A, B, and AB to
be converted into type O .
These enzymes were found following an extensive screening process of 2,500
fungal and bacterial isolates. Eventually:
• An active α-N-acetylgalactosamidase, which converts group A to group O, was
found in the gram-negative bacterium Elizabethkingia meningoseptica.
• converts group B to group O, was found in the gram-negative bacterium
Figure (4) : Group O red cells are called ‘universal’ because they are suitable for transfusion to individuals of all ABO groups. Group A
red cells can be given safely only to A and AB individuals, and group B red cells can be given only to B and AB individuals. Modification
of A and B red cells by novel glycosidases removes the immunodominant sugars (GalNAc and Gal), in principle rendering them suitable
for transfusion to anyone.
From:- medical biotechnology by
Bernard R. Glick , Terry L. Delovitch
& Cheryl L. Patten :- capture 9
((Protein Therapeutics : Enzyme ))
• Ulmer, G. S., A. Herzka, K. J. Toy, D. L.
Baker, A. H. Dodge, D. Sinicropi, S. Shak,
and R. A. Lazarus. 1996. Engineering actin-
resistant human Dnase I for treatment of
cystic fi brosis.
• Alkawash, M. A., J. S. Soothill, and N. L.
Schiller. 2006. Alginate lyase enhances
antibiotic killing of mucoid Pseudomonas
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• Article , Enzyme Therapy: Current
Challenges and Future Perspectives
by:- National Center for
• Article , Phenylalanine degrading
enzymes-displayed probiotics are
more effective live biotherapeutic
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