ANTIBODIES / IMMUNOGLOBULINS

ANTIBODY

Another term for is immunoglobulin based on the fact that these molecules are specialized globular proteins that play a vital role in immunity.

IMMUNOGLOBULIN

Another term for antibody is _____ based on the fact that these molecules are specialized globular proteins that play a vital role in immunity.

ANTIBODY OR IMMUNOGLOBULIN

Are glycoproteins that are composed of:

• 86% to 98% polypeptide and

• 2% to 14% carbohydrate.

• 86% to 98% polypeptide and

• 2% to 14% carbohydrate

Antibodies are glycoproteins that are composed of: 

86% to 98%

How many percent of polypeptide is in an antibody?

2% to 14%

How many percent of carbohydrate is in an antibody?

ANTIBODY OR IMMUNOGLOBULIN

Main humoral element of the adaptive immune response because of a number of different functions:

1. Antigen recognition

2. Opsonization

3. Complement activation

1. Antigen Recognition

2. Opsonization

3. Complement Activation

FUNCTIONS OF ANTIBODY:

ANTIGEN RECOGNITION

There is direct binding between the intact antigen and antibody

FUNCTIONS OF ANTIBODY

OPSONIZATION

Function to hasten or enhance phagocytosis

FUNCTIONS OF ANTIBODY

ANTIBODY OR IMMUNOGLOBULIN

Constitute approximately 20% of plasma proteins, and can be detected by performing serum protein electrophoresis.

20%

Antibodies constiture approximately how many percent of plasma proteins?

serum protein electrophoresis

Antibodies can be detected by performing?

Agarose gel

In pertaining to electrophoresis, the serum sample is placed on an ___

GAMMA GLOBULINS

electrical current

An _____ is applied to separate out the proteins

GAMMA GLOBULINS

8.6

Most serum proteins can be separated at a pH of ___ based on their charges and size.

GAMMA GLOBULINS

• alb (albumin)

• ɑ1 (alpha 1)

• ɑ2 (alpha 2)

• β (beta)

• γ (gamma)

There are 5 distinct bands/regions that will appear:

GAMMA GLOBULINS

slowest; neutral; γ (gamma) region or in the γ (gamma) band

Immunoglobulins being the (fastest/slowest) moving proteins and they have a charge that is close to ____, it will appear primarily in the ____.

gamma globulins

Aside from being named antibodies, immunoglobins are also termed ____.

four-chain tetrapeptide

All immunoglobulin molecules are made up of a basic _____ unit.

heavy or H chains

Two large chains in an immunoglobin molecule are called?

light or L chains

Two small chains in an immunoglobin molecule are called?

disulfide bonds

The pair of identical Heavy Chains and the pair of identical Light Chains are held together by _____. Contains a single variable region and one or more constant regions present in every chain

• Single Variable region

• One or more Constant region

What regions are present in every immunoglobulin chain?

50,000 – 70,000 Daltons

Molecular weight of the heavy-chain (H chain):

• IgG: γ (Gamma)

• IgM: μ (Mu)

• IgA: α (Alpha)

• IgE: ε (Epsilon)

• IgD: δ (Delta)

Constant regions of the H chain are unique to each class and give each immunoglobulin type its name:

Gamma

γ

Mu

μ

Alpha

α

Epsilon

ε

Delta

δ

22,000 Daltons

Molecular weight of the light chain (L chains):

1. Kappa (κ) chains

2. Lambda (λ) chains

Two main subtypes of L chains:

Kappa (κ) chains

More predominantly seen (60%)

TWO MAIN SUBTYPES OF L CHAINS

Lambda (λ) chains

40%

TWO MAIN SUBTYPES OF L CHAINS

2:1

Subtype ratio (κ to λ):

200 and 220 amino acids; 111

Each subtype L chain contained between ____, and from position number ____

Kappa

κ

Lambda

λ

60%

Kappa (κ) chains percentage

40%

Lambda (λ) chains percentage

LIGHT CHAIN (L CHAIN)

Smaller chain of the antibody molecule

LIGHT CHAIN (L CHAIN)

Identify if (H CHAIN OR L CHAIN):

MW: 22,000 Daltons

LIGHT CHAIN (L CHAIN)

Identify if (H CHAIN OR L CHAIN):

Found on all types of immunoglobulin molecules but do not extend the full length.

LIGHT CHAIN (L CHAIN)

Identify if (H CHAIN OR L CHAIN):

Only has 1 variable (VL) & 1 constant (CL) region.

HEAVY-CHAIN (H CHAIN)

Identify if (H CHAIN OR L CHAIN):

Larger chain of the molecule

HEAVY-CHAIN (H CHAIN)

Identify if (H CHAIN OR L CHAIN):

MW: 50,000 – 70,000 Daltons

HEAVY-CHAIN (H CHAIN)

Identify if (H CHAIN OR L CHAIN):

Extends the full length

1. VH

2. CH1

3. CH2

4. CH3

Heavy Chain Sequencing:

VARIABLE REGION

Identify if its Variable Region / Constant Region:

Located in the amino terminal end of your antibody molecule.

VARIABLE REGION

Identify if its Variable Region / Constant Region:

Defines the specificity of an antibody

VARIABLE REGION

Identify if its Variable Region / Constant Region:

First 110 amino acids

CONSTANT REGION

Identify if its Variable Region / Constant Region:

Found on the carboxy terminal end of the antibody.

CONSTANT REGION

Identify if its Variable Region / Constant Region:

Starts from the 111th amino acid onwards for both H & L chains.

CONSTANT REGION

Identify if its Variable Region / Constant Region:

Can typically be divided into 3 or more ____ with very similar sequences, designated as CH1, CH2, CH3

amino terminal end

Where is the variable region located in your antibody molecule?

carboxy terminal end

Where is the constant region located in your antibody molecule?

IgM

Has an extra 4th domain (CH4)

• Fc Fragment

• Fab Fragment

TWO TYPES OF FRAGMENT OF ANTIBODIES:

FC Fragment

Identify what type of fragment (Fc / Fab):

Spontaneously crystallizes @ 4C

FC Fragment

Identify what type of fragment (Fc / Fab):

Represent the carboxy-terminal halves of two H chain

FC Fragment

Identify what type of fragment (Fc / Fab):

No antigen binding capacity

FC Fragment

Identify what type of fragment (Fc / Fab):

Responsible for the biological activity of the molecule (effector functions):

• Opsonization

• Complement fixation

Complement fixation

Most important function of the Fc fragment

Fab Fragment

Identify what type of fragment (Fc / Fab):

Function is antigen binding 

Fab Fragment

Identify what type of fragment (Fc / Fab):

(1) light chain & half of the heavy chain held together by disulfide bonds

Fab Fragment

Identify what type of fragment (Fc / Fab):

Each fragment represents one antigen binding site

4°C

Fc fragment crystallizes at what temperature?

HINGE REGION

The segment of heavy chain located between the CH1 and CH2 regions

between the CH1 and CH2 regions

Where is the hinge region located?

HINGE REGION

Rich in hydrophobic residues and has high proline content

PROLINE

This confers flexibility of the hinge region

Susceptible to proteolysis because of the presence of disulfide bonds

HINGE REGION

Is the area where the antibody is most susceptible

Because it contains disulfide bonds

Why is the hinge region the area where the antibody is most susceptible?

1. Allows the 2 antigen binding (Fab) fragments to operate independently 

2. Assists in the effector functions such as activation of the complement pathway

3. Allows bending in Fab fragments to be able to attach to antigens

FUNCTIONS OF THE HINGE REGION:

IgD

Have very long hinge region (longest)

IgM, IgE

DO NOT have a hinge region

CARBOHYDRATE PORTION

Attached in the CH2 domain

CH2 domain

Where is the carbohydrate portion attached?

1. Increasing the solubility of immunoglobulin

2. Providing protection against degradation

3. Enhancing functional activity of the FC domains.

FUNCTIONS OF THE CARBOHYDRATE PORTION:

Enhancing functional activity of the FC domains.

Is the most important function of the carbohydrate portion because it is responsible for the effector function of the antibody molecule

HYPERVARIABLE REGIONS (HVR) / COMPLEMENTARITY DETERMINING REGIONS (CDRs)

3 _____ are found within variable regions of H and L chains

variable regions of H and L chains

3 HVRs are found within?

COMPLEMENTARITY DETERMINING REGIONS (CDRs)

Hypervariable Regions (HVR) is also called?

HYPERVARIABLE REGIONS (HVR) / COMPLEMENTARITY DETERMINING REGIONS (CDRs)

They are responsible for the diversity of immunoglobulin molecules

middle of the HVR/CDR, specifically between the two HVR/CDR of your heavy and light chains

What portion of you HVR/VDR where the antigen binds?